DR. R. W. SHUFFLDT, 
U. S. ARMY. [ EXTRACTED FROM THE ANNUAL REPORT OF THE COMMISSIONER 
OF FISH AND FISHERIES FOR 1883. ] 
THE 
■f 
OSTEOLOGY OF AMIA CALVA, 
INCLUDING 
CERTAIN SPECIAL REFERENCES TO THE 
SKELETON OF TELEOSTEANS. 
BY 
R. W. SHUPELDT. 
WASHINGTON: 
GOVERNMENT PRINTING OFFICE. 
1885. 000.—THE OSTEOLOGY OF AMIA CALYA: INCLUDING CER- 
TAIN SPECIAL REFERENCES TO THE SKELETON OF TELE0S- 
TEANS. 
By R. W. Shufeldt, M. D., 
Captain Medical Corps, U. S. Army. 
The present paper will be divided into two parts j of these, Part I will 
consist of a translation of the admirable article of Dr. M. Sagemehl, 
entitled 11 Beitrdge zur vergleichenden Anatomic der Fischef' the first con- 
tribution given us being “I. Das Cranium von Amia calva, L.” This 
carefully written essay appeared in the second part of the ninth volume 
,of the Morphologisches Jahrbuch, for the year 1883. It is illustrated 
with one double-page, beautifully executed plate. The twelve figures 
in this plate I have had, through the kindness of Professor Baird, care- 
fully copied by Mr. H. L. Todd, the artist of the Fish Commission and 
Smithsonian Institution. They appear in their proper places in the 
plates illustrating this article with their explanations set opposite to 
them. 
In Part II it is my intention to review the conclusions arrived at by 
Bridge, after his study of the skeleton of this interesting form. This 
anatomist published his well known memoir in the Journal of Anatomy 
and Physiology (Yol. XI, 1877, pp. 605-622, Plate XXIII), six years 
before Dr. Sagemehl’s results appeared in the Jahrbuch. In this part, 
too, I will bestow a passing glance upon the monograph of Henricus 
Franque,1 and compare his figures with those given by the above 
authors. Beyond this, however, it is not my intention to pass further 
into the literature of the subject, as the short and unsatisfactory 
accounts given by the older writers would avail us nothing here. 
Finally, I propose to present a few observations of my own, which have 
been the result of an examination of a skeleton of Amia, carefully 
prepared from a specimen of this fish which I captured in the vicinity 
of Xew Orleans, La., during the summer of 1883. This preparation was 
done for me in the most skillful manner by Mr. J. L. Wortman, the 
anatomist of the Army Medical Museum, of Washington. A few figures 
will be presented in this part, illustrating points that do not appear in 
Dr. Sagemehl’s article. 
1 Amice Calvce Anatomiam, Berolini, 1847. 
1 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
2 
PART I. 
Ever since 1845—when Carl Vogt2 demonstrated that Amia calva, L. 
differed in the structure of its heart from all known bony fishes, being 
like the cartilaginous fishes in this respect; and since Johannes M filler,3 
noting this circumstance, separated this remarkable fish from the 
Clupeoids, with which it had formerly been classed, adding it to his and 
L. Agassiz’s established sub-class of Ganoids—the attention of anat- 
omists has been steadily directed towards this form. 
A number of works touching upon nearly all parts of the anatomy of 
Amia have made their appearance, so its structure is at present better 
known than that of most bony fishes. It is quite remarkable that the 
cranial anatomy of this Ganoid has not received proper attention, as it 
is by no means a rare fish in collections. The memoir by Bridge,4 pub- 
lished in 1877, is in my opinion the only one in which the subject has 
been at all fully described. 
Upon the suggestion of Privy Counselor Professor Gegenbaur, T 
undertook the task of re-examining the crania of the Teleostei, especially 
in the Physostomi and the Anacanthini, and in looking for a form in 
which the various differences in the structure of the skull could best be 
judged, my attention was drawn to Amia. In fact, a careful study of 
the cranium of this fish showed that several diverging series of skull- 
types could easily be traced from it. On the other hand, the task of 
tracing the conditions of the cranium of the Teleostei from more simply 
constructed types—such as the Selachians offer—I found the Amia to be 
an excellent transitory form for the purpose. The careful descriptive 
work of Bridge, with whom I concur in the majority of points, so far 
as the actual conditions are concerned, does not suffice for this special 
purpose. Certain points of organization, which at the first glance ap- 
pear to be incorrect, and the significance of which only become appar- 
ent after comparisons with other forms, he has left entirely unnoticed. 
Furthermore, in his descriptions he has kept strictly within the limits 
of his title, perhaps for lack of material, describing only the bones of 
the skull and entirely neglecting the surrounding soft parts, in which 
I recognize the necessary elements to complete the configuration of the 
skull. Finally, in my opinion, Bridge has not been fortunate in his 
descriptions of several of the bones of the skull in Amia. 
Taking all this into consideration, I decided to present a comparative 
description of the skull of Amia. At the same time I believe I will be 
2Annales des Sciences Naturelles, T. IV, 1845. (I have changed the numbering of Dr. 
Sagemehl’s foot-notes so as to accommodate them to the present article.—Trans.) 
3 Cber den Bau und die Grenzen der Ganoiden. Abh. d. k. Akad. d. Wissenschaften z. 
Berlin vom Jalire 1844. Berlin, 1846. Nachschrift, pag. 204. 
4The Cranial Osteology of Amia calva. Journ. of Anatomy and Physiology, Yol. 
XI, 1877, pages 605-622. THE OSTEOLOGY OF AMIA CALVA. 
able to discuss several questions of a more general nature, which are of 
prime importance when taken iu connection with my work upon the 
crania of the Teleostei, soon to be undertaken. It only remains for me 
to justify myself for having confined myself in this work, as I will in 
those of the future, strictly to the cranium, and for having but touched 
lightly upon those parts of the visceral skeleton connected with it; and 
that, too, only so much of it as wag necessary to complete the form of 
the skull. Such partiality would hardly be justifiable were one consid- 
ering the forms the cranium assumes in the higher vertebrates. 
This is entirely different in the class Pisces. The visceral skeleton 
here has, in so far as the cranium is concerned, preserved a certain 
independence, and in consequence its form has been much less in- 
fluenced, less so than other organic systems, as for example the nervous 
system, the muscular system, and particularly the organs of sense. 
There is yet another objection that might be brought forward, and 
that is, that I have paid but little attention to the literature of the sub- 
ject, particularly the older literature. In my allusion to facts long 
known—and, as I assume, of facts well known—it seemed to me entirely 
superfluous to continually cite authorities. Such a course would have 
rendered my subject-matter diffuse and unwieldy, without adding any- 
thing useful. The literature relating to it, contained in the more recent 
and less known works, and which refers to the discussion of purely 
special points, I have in every instance conscientiously cited. 
Through the unbounded liberality of Privy Counselor Mr. Gegenbaur, 
to whom 1 here express my profound thanks, I have been enabled to 
examine five specimens of Amia, the smallest of which was 36em, the 
largest 57cm long. 
In viewing an unprepared head of Amia calva one can already dis- 
tinguish the superficial plates of bone that overlie the cranium, they 
being merely covered by an extremely thin cutis.5 
The sculpturing of the superficies of these bony plates is quite char- 
acteristic, consisting of sharply-defined and numerous ridges, which 
start from the center of each bone, to radiate outwards to the peri- 
pheries. After the thin skin covering them has been carefully removed 
one recognizes the limits of the several bones with requisite distinct- 
ness. Three pairs of bony tables, situated one behind the other, first 
meet the eye, of which the foremost possesses the greatest and the 
hindmost the least longitudinal extension. 
The foremost of these pairs of plates consists of two bones, each of a 
quadrilateral outline, being joined together mesially by a strong dentated 
suture. (Plate I, Fig. 1.) The lateral borders of these bones arch over 
5If Bridge (loc. tit., page 606) describes tbe surface of these bones as “highly pol- 
ished,” and further says “they are destitute of any covering of soft skin,” he is in 
error. One can easily convince himself, from a microscopical examination, that all of 
these overlying plates of the skull in Amia are not only covered by an epidermis— 
which is also present is Lepidostem and Polypterus—but undoubtedly also possesses a 
very thin covering of cutis. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
tlie orbits, while their anterior lateral angles rest upon the antorbital 
processes. In view of this arrangement this pair of bones are charac- 
terized as the frontalia6 [frontal plates]. 
Behind these two bones, follow two others of an approximately quad- 
rilateral outline, which like the preceding pair are connected together 
in the middle line by a dentated suture. These are undoubtedly the 
ossa parietalia [parietal plates], which in Amia, as in several other bony 
fishes, are suturally united mesiad7. (Plate I, Fig. 1.) 
On either side of the parietalia and of the posterior part of the fronta- 
lia is found a longitudinally placed bone (Plate I, Fig. 1, ISq.), which 
corresponds in all respects with the os squamosum of the Teleostei.8 
Articulating with its hinder border with the squamosal on either side, 
and being situated at about the middle of the latter half of the frontal, 
we observe another osseous plate, with its long diameter placed longi- 
tudinally. It is the osseous plate that overlies the continuation of the 
post-orbital, and is the post-frontal (Plate I, Fig. 1, and Plate II, Figs. 5 
and 0, Psf.). A similar, only smaller, bone-plate, extensively sculptured, 
articulates with the anterior lateral angle of the frontal, and is the 
superimposed plate that represents the prefrontal (Plate I, Figs. 1, 2, 
and o, Prf.). While the bony plates just described are firmly articulated 
with one another, and are also in intimate relation with the true cranium 
beneath, or are even blended with it, the two rather small osseous plates 
(Plate I, Fig. 1, Ex.) situated behind the parietals and squamosals, and 
meeting each other in the middle line,9 are connected only with the 
bones in front of them by means of dense ligamentous bands. Nor 
6Ah regards tlie determinations of these bones, I have adhered strictly to the 
names used for them by Gegenbaur. It is of course universally known that these 
names, now long in use, do not express any homology whatever with the correspond- 
ingly named bones of the higher vertebrated animals. I am of the opinion that a 
complete homology exists for only a very few of the bones of fishes when compared 
with those of the higher vertebrata. There is not positive proof for a single one of 
them at the present writing. The most rational thing to do under the circumstances 
would be to introduce, if possible, a new and neutral nomenclature for the bones of 
the skull in fishes ; yet I did not think myself justified in introducing such an inno- 
vation, which at any rate, so long as an exhaustive knowledge of the bones of the 
skull in fishes is not complete, could only be provisional, and I have therefore con- 
tented myself with the old names. 
7 Bridge, on whose specimen this mesial suture between the Paritalia had worn 
away, bestows, in consequence, upon the blended bony plates the name of “ dermo- 
supraoccipitale,” a name which in any event is inadmissible. On seven specimens of 
Amia, examined by me for the special purpose of looking into this condition, I have 
invariably found the median suture to be present, agreeing in this particular with the 
descriptions given by Owen and Franque, and I must consider the condition as found 
by Bridge as an individual anomaly, to which no further significance need be at- 
tached. 
8 Bridge takes this pair of bones for the parietalia because they lie upon either side 
of his dermosupraoccipitale. 
9 If Bridge intends to convey the idea that these plates do not meet each other in 
the middle line, he is in error; his own drawing (Plate XXIII, Fig. 1) proves to the 
contrary. THE OSTEOLOGY OF AMIA CALVA. 
have they anything whatever to do with the primoidal-cranium, and 
they are even separated from the exoccipitals by connective tissues, 
though they overlap these bones to some extent. The greater part of 
one of these bones laps over one of the bones of the shoulder girdle, 
which latter rests with a mesially-directed process upon the hinder 
border of the exoccipital, while its remaining process, directed forwards, 
is attached by a strong ligament to the intercalare. This bone (Plate 
I, Fig. 1, Sc.) corresponds in all respects with the suprascapula10 found 
in nearly all of the Teleostei. 
Among the Teleosteans one quite constantly finds, between the pro- 
cesses of the suprascapula, a very superficially-situated dermal bone, 
which was first differentiated by Stannius from the supratemporal bone, 
which articulates laterally with the squamosal, and has been termed the 
extrascapula. This bone usually is not very large, yet in a few cases, as 
for example in Macrodon, it attains quite a considerable size; it then 
resembles in a great measure the bone as just described for Amia, and 
it is only to be distinguished from it in that it does not meet its fellow 
in the middle line. One will therefore hardly go astray in regarding 
the bone in Amia, designated in Plate I, Fig. 1, as Esc., as homologous 
with the extrascapula of the bony fishes. 
The nasal region of Amia is covered by five small dermal bones, which 
are separated posteriorly from the frontal plates by a small transverse 
strip of cutis. 
The dermal bone (Plate I, Fig. 1, Etli.), placed most anteriorly of this 
group, has the form of an equilateral triangle, with the apex directed 
backward, and with a somewhat spreading base. It lies more deeply 
seated in the skin than the rest of these bones that overlie the cranium, 
but nevertheless it shows traces of the sculpturing that characterizes 
them all. Posteriorly, and to either side of this unpaired osseous plate, 
lie a couifie of small bones (Plate I, Fig. 1, Na.) of which the two medial 
ones are somewhat the larger pair. These are separated anteriorly by 
the azygos bone, just referred to, penetrating between them; behind, 
they meet each other in the median line. On either side of these dermal 
bones lie two smaller ones (Plate I, Fig. 1, An.), of which no special notice 
need be taken. The four bones just described, more especially the medial 
pair, form the covering to the nasal cavity. Among the three bones 
designated by Eth., Na., and An. there remains, where they come to- 
gether anteriorly, a small opening which leads to the rhinal chamber, 
and corresponds to the anterior nasal aperture of Amia. The posterior 
nasal opening is far removed from the anterior, being situated at the 
posterior lateral angle of the bone designated by Na. The interpreta- 
tion of the dermal plates just described is not difficult. 
The t wo posterior medial dermo-bones, holding, as they do, a position 
in front of the frontals and above the narial depressions, correspond or 
answer to the nasal bones of osseous fishes. There is yet another con- 
10 Suprascapula of Cuvier; omolita of Geoffroy and Stannius. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
6 
dition of these bones that supports this statement, viz, their relation to 
the mucus canals of the head.11 
Among the Teleostei the anterior branch of the mucus canal, imbed- 
ded in the frontal bone, begins with an opening which is situated to 
the inside of the anterior nasal aperture. Its course in the nasal is 
backwards, aud then it passes through the frontal, in which it throws off 
several side branches. 
This portion of the mucus canal bears exactly the same relations to 
the bones in question in Amia as in the nasal among the Teleosteans, 
as may be seen by referring to Plate I, Fig. 1. 
The mucus canals can also be utilized in defining both lateral bones. 
The main branch of the mucus canal, imbedded in the same, unites with 
the canal of the suborbital arch, and only a small lateral branch anas- 
tomoses with the mucus canal of the frontal. This condition reveals 
the fact that the bone just mentioned must be the first piece of the sub- 
orbital arch somewhat removed from its usual position—the antorbital. 
The middle nou-parial piece can also be determined without difficulty. 
In it we see a rudimentary ethmoid which has abandoned its customary 
site and relations with the frontalia, owing to the unusually developed 
nasal bones. So Bridge has likewise considered it; in fact, one could 
hardly regard it in any other light, unless choosing the very improba- 
ble assumption that the ethmoid—very constant elsewhere—is entirely 
absent in Amia, and that this fish is provided with a peculiar prenasal 
bone that never occurs in other fishes. Our determination is undoubt- 
edly correct, as we find in Potypterus an identically similar bone, 
though here it is connected with two small processes of the frontalia 
that enter in between the nasals.12 
All of the bones just described that overlie the cranium, with the sin- 
gleexception of the prefrontal, are pierced by a system of mucus canals, 
which are worthy of a closer consideration (see Plate I, Fig. 1). 
As already mentioned above, a large mucus canal commences, mesiad, 
by the anterior nasal aperture to follow a course first in the nasal, then 
through the entire length of the corresponding frontal, to terminate in 
the extreme anterior portion of the parietal, on the surface of which its 
mouth is to be found. 
Tlie right and left canal are connected anteriorly by means of a trans- 
verse auastomosis which passes through the ethmoid. During its course 
through the posterior part of the frontal the mucus canal just described 
throws off a lateral branch, which passes through the postfrontal, and, 
being confined between the bones of the orbital arch, passes around the 
111 desire to mention, at this point, that hitherto the relation of the mucus canals 
to the bones of the cranium have hardly been given a thought, and yet they deserve 
a closer study, as these relations are very constant, and in questionable cases they can 
be used to determine doubtful homologies. 
12 Cf. the representation of Muller, Structure and Limits (Grenzen) of the Ganoids, 
PI. I, Fig. 1. THE OSTEOLOGY OF AMIA CALVA. 
eye, reaches the preorbital, and terminates laterally near the anterior 
nasal aperture. 
From the mucus canal leading to the orbital arch another canal takes 
origin, beginning in the frontal, passing through the entire length of 
the squamosal, to enter the extrascapula and suprascapula. After 
passing through the suprascapula it becomes the mucus canal of the 
lateral line, passing on to terminate at the tail. Both of these canals, 
just referred to, are united by a transverse anastomosis, which is im- 
bedded in the substance of the extrascapula. During its course through 
the squamosal a branch directed laterally arises from this canal. This 
branch enters the preoperculum, passing through the entire length of 
this bone to enter the mandible beyond, and eventually join the fellow 
of the opposite side, which it meets at the symphysis. All these mucus 
canals send off numerous ramifications of smaller canals, arranged in 
several longitudinal rows, which terminate on the surface of tlie head in 
minute openings. 
Taking into consideration their superficial location, the peculiar sculp- 
turing of their surface, and the possession of mucus canals, the bones 
we have just described are unquestionably characterized as ossifications 
of the skin—as dermal bones. In making any attempt to remove these 
dermo-bones one recognizes the fact that their relations to the chondro- 
<jranium are very different. 
The ethmoid, the nasals, and the preorbitals13 do not come in contact 
at all with the same, but are separated from it throughout their entire 
extent by soft parts. 
On a microscopical examination of cross-sections made from one of 
these bones (take for example the extrascapula) one can distinguish 
.a superficial layer from a deep one. The latter consists of osseous 
lamella}, which are piled up parallel with the bony plane, and which are 
interrupted by others, arranged concentrically around the Haversian 
canals. 
This deeper bony layer gives passage to quite a number of capacious 
Haversian canals and is supplied pretty generously with bone corpuscles. 
The superficial layer of these dermal bones is characterized, when com- 
pared with the one just described, by a much denser tissue, by a small 
number of Haversian canals, by an almost entire absence of bone cor- 
puscles, and, what is most important, by the existence of numerous and 
very minute dentine tubelets (Dentinrohrchen) wThich penetrate it from 
the surface of the bone. Yet I wish to explicitly state that one cannot 
make out the exact boundary between these two layers with any cer- 
tainty. 
Tlie frontals, parietals, and squamosals are in more intimate relation 
with the skull. In part, these are quite closely connected with the car- 
tilaginous cranium, and are separated from it simply by a layer of thin 
-connective tissue. Histologically they remind one very much of the 
13 This applies also to the extrascapular, the suprascapular, and the supraclaviculas. KEPORT OF COMMISSIONER OF FISH AND FISHERIES. 
bones of the first group. The two osseous layers can also be distin- 
guished in them, but the inferior one is better developed and more plen- 
tifully supplied with Haversian canals, so that it becomes quite spongy 
in character. As already stated, they are separated from the underlying 
cartilage by a thin layer of connective tissue, through which ramify a 
numerous set of vessels, and in which are found pigment cells. 
Finally, the postfroutals and prefrontals present us true “ primary” 
ossifications of the primoidal cranium, which cannot be removed without 
injury to it, and which only remind us of their original development as 
dermal bones by their superficial locatiou and by their sculptured sur- 
faces, the former also by their having mucus canals. 
The conclusion which we arrive at after our examination of these two 
bones in Amia, and which they afford, is so unique and so unlike the 
usual conditions that characterize those specific differences between 
dermal bones and the ordinary ossifications of the true skeleton, that it 
is easily perceived how Bridge was induced to separate each of these 
bones into two components, and to distinguish the true—corresponding 
to the homologous bones of the Teleostei—prefrontal and postfrontal, as 
well as the u dermoprefrontal and derinopostfrontal,” covering the same* 
An unprejudiced examination at once convinces us that the conclusions 
arrived at by Bridge do not agree with the actual condition of things. 
The plates of these bones, visible on the surface of the cranium, as well 
as the outer layer of all the other dermal bones, undoubtedly consist of 
a compact and very hard bony substance, while those parts which are 
more deeply situated are more cancellous in texture; still the transition 
of one to the other is gradual, and the superior plate cannot be removed 
without breaking the bone. 
Here a rare case presents itself—up to the present time almost universally 
doubted—in which hones that on their surface present all the characteristics 
of dermal bones have acquired relations with the true skeleton through 
their more deeply situated parts or structure, and in consequence are in part 
dermal and in part true bones. 
Another group of bones is to be seen—partly, also, without dissection— 
from the cavity of the mouth. Lying in the median line and longitud- 
inally placed upon and belonging to the parasphenoid is an osseous 
strip that is entirely covered over with a growth of firmly implanted 
and small conical teeth.14 Between these teeth the bone is covered by 
a very thin layer of mucous membrane, which is only to be discovered 
after careful search. 
Situated anterior to these median bony strips, there is on either side 
a number (from 17 to 22) of strong conical teeth, which are supported 
by the vomer. As the interstices among these teeth are filled in by a 
thick mucous membrane, nothing can be seen of the bones from an 
14 When Bridge speaks of roughness (asperities) of the parasphenoid, he does not 
convey to us the correct idea or condition. This roughness is caused by these true 
teeth, and of this fact Franquewas already cognizant. THE OSTEOLOGY OF AMIA CALYA. 
external view. Similar bone-plates, provided with finp little teeth, such 
as those just described for the parasphenoid, are found upon the pala- 
tine, upon the three pterygoids, and upon the splenial of the mandible. 
After the excellent investigations of Leydig15 and O. Hertwig16 a par- 
ticular reason is hardly required if I place the parasphenoid and the 
vomer, as ossifications of the mucous membrane of the mouth, opposite 
the dermal ossifications and the true ossifications of the skull. 
In respect to this, it seems to me that the condition found to exist 
in Polijpterus is of peculiar significance; in this form, according to 
Leydig’s investigations, all the boues of the buccal cavity are covered 
over by the epithelial layer solely. The Amia, where the ossifications 
beneath the epithelium are likewise covered by a layer of connective 
tissue, constitutes an excellent example, so far as this condition is con- 
cerned, of the transition stage between this form and the majority of 
bony fishes, in which the parasphenoid and vomer are hidden beneath 
the thick mucous membrane of the mouth. 
After the cranium has been skeletonized, the parasphenoid and the 
parial vomer can be easily discerned. 
The parasphenoid (Plate I, Fig. 2, ps.) is aflat bone, having the form of 
a cross. Its stem extends from the hindermost extremity of the skull 
to the antorbital, and very near its middle it gives off two branches, 
which extend laterally and upward alongside the postorbital, and form 
the posterior boundary of the orbit. 
The posterior extremity of the parasphenoid is deeply cleft, thus 
allowing a small triangular portion of the basi cranii, represented by 
the basioccipital, to come into view upon a basal aspect of the skull. 
That part of the bone which is provided with teeth, and which in 
different individuals varies with regard to its anterior and posterior 
extension, lies mesially between the two branches. 
In front of the parasphenoid are found the two vomers (Plate I, Fig. 
2, vo.), articulating with each other in the middle line. They are flat 
osseous plates, placed longitudinally, with their anterior thirds armed 
with stout teeth. Their posterior moiety covers the anterior part of the 
inferior aspect of the parasphenoid. 
If the statement that the parasphenoid originally bore teeth over its 
entire surface be correct—and so many facts have been adduced in its 
favor that its correctness can hardly be doubted—the overlapping of 
the vomer on this bone must be a primitive state of affairs. In fact, if 
one compares this condition of Amia, with its parial vomer, with the ar- 
rangement in bony fishes, where the vomer is known to be always non- 
parial, hardly a doubt but that Amia represents the primitive condition 
remains. 
l6W. Leyclig, Beitrag z. mikroskop. Anatomie v. Polyp ter us. Zeitschr. fiir wins Zool., 
Bd. V. 
160. Hertwig, Das Zahnsystem der Amphibienf. mikroskop. Anatomie. Bd. XI, suppl. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
Leaving entirely out of consideration the arguments that can be ad- 
duced in favor of a progressive development of Amia in the direction of 
the bony fishes, and that the division of a bone into several parts is an 
hypothetical process, the positive proof has been given us by Walther17 
that the vomer of the pike is a parial ossification. Yet the present posi- 
tion of the vomers in Amia is not the primitive one, and in order to get 
around all difficulties involved in this question we must assume that 
in still more pristine forms both these bones occupied a position more 
remote from the mesial line, on either side of the anterior extremity of 
the parasphenoid, as in many existing Amphibia. 
The conclusion arrived at from these inferences—taken in connection 
with the fact that the vomerine and palatine teeth of fishes are situated 
in one and the same line, lying in the same arch—gives some coloring 
to the supposition that the vomers of fishes originally constituted the 
anterior overlapping segments of the palatine arch, as has been proven 
by Hertwig for the Amphibia. 
To the “cover-bones” of the skull in Amia yet belongs another piece, 
that with other forms is not so intimately related to the primodal cra- 
nium. It is the intermaxilla (Plate I, Fig. 1, and Plate II, Fig. 6, 8m.). 
This is to be seen extended upon the cartilaginous base of the rhinal 
chamber, proceeding backwards from its arched and compact alveolar 
process; this thin osseous plate encroaches to no small extent upon the 
antorbital region. 
In the posterior portion of the nasal depression this plate is pierced 
by a large foramen for the passage of the olfactory nerve (Plate I, Fig. 
1, ol). 
The integrity of the cartilaginous cover of the primoidal cranium of 
Amia is thoroughly preserved throughout, being devoid of fenestrm or 
other breaches in its substance of any kind whatever. 
In outline it resembles a triangle placed longitudinally, with its apex 
cropped off anteriorly; it is generally level, and marked only by pit-like 
impressions at the posterior lateral angles, and by a number of project- 
ing processes, which are more or less ossified. The two anterior ones 
are the antorbital processes (Plate I, Fig. 1), with their ossifications 
already described—the prefrontals. At about the middle of the skull- 
cover the postorbital processes project out laterally at each side, to- 
gether with their ossifications, also described as the postfrontals (Plate 
I, Fig. 1). 
The prominent posterior lateral angle of the primoidal skull is oc- 
cupied by the intercalare [opisthotic] (Plate I, Fig. 1, Jc.). 
As we proceed towards the median line from the angle formed by the 
intercalare we find rising on either side another process, situated not 
quite so far behind, that is formed by the exoccipital (Plate I, Fig. 1, Ex.). 
Between these processes, formed by the intercalare and exoccipital, ex- 
17 J. Walther, Die Entivicklung der Deckkurcken am Kopfskclet des Hechtes. Jenaische 
Zeitschrift /. Naturwiss., Bd. XVI, 1882. 11 
THE OSTEOLOGY OF AMIA CALVA. 
tensive fossm are found on the skull, that extend well anteriorly to- 
wards the frontal region (Fig. 1). 
As the dermal bones, occupying their respective places, the squa- 
mosal and lateral margin of the parietal span this depression as the arch 
of a bridge, it gives rise to a cavity between the primoidal cranium and 
its cover-bone, the opening of which is upon the posterior aspect (Plate 
II, Fig. 6, tg.18) and into it enters, to be attached to the occiput on either 
side, a part of the muscle of the dorsum of the trunk. 
This depression, which forms so striking a feature of the skulls in the 
Teleostei, I here propose to name the temporal fossa.19 
Projecting from the middle line posteriorly there is a short cartilagi- 
nous process (Fig. 3, Oc.20) that occupies precisely the same position 
that the superoccipital does in the Teleostei. The last mentioned bone 
is wanting in the Siluroids and Dipnoi. From the hinder boundary of 
the vault of the skull it is produced downwards and backwards, and 
finally is drawn out as a cylindrical prolongation of the same, in which 
is contained the posterior part of the medulla oblongata and the anterior 
commencement of the spinal cord. 
The occipital region21 of Amia is, so far as a comparison with bony 
fishes teaches us, remarkably drawn out longitudinally, and this pro- 
longation, the cause and significance of which will be discussed further 
on, concerns chiefly the region posterior to the foramen for the vagus. 
18 This is given in the text of the original as Th. and I here correct it to tg.—Trans. 
19 This point is the proper one for us to take a careful look into the relations of the 
squamosal to the primoidal cranium. This hone rests hy its lateral border only upon 
that crest of the primoidal skull which is directed upwards and outwards and forms 
the lateral boundary of the temporal fossa. Now, although the squamosal in Amia, 
as already stated, is a dermal bone, which appears only to be resting upon the pri- 
moidal cranium, it would be impossible to remove it without injury. This is the site 
it occupies: from the lateral margin of the bone are developed two osseous ridges, 
which are directed downwards and to some extent towards the median line, and have, 
when articulated, the two corresponding sharp cartilaginous crests of the skull in- 
serted between them. The lateral ridge of the squamosal, of the two mentioned ones, 
is juxtaopposed to the lateral surface of the skull, and is carried from the margin of 
the bone downwards to the hyomandibular articulation. The remaining or mesial 
ridge lies in the temporal fossa. This condition is significant in so far that among 
the Teleostei it is only through the lateral margin of the squamosal, that the cartil- 
ages are wedged apart, and the firm union of the bone with the primoidal cranium 
takes place. 
20 This is Co. in the original text, and it has been corrected here to Oc. In either 
event it is not quite clear what Dr. Sagemehl intends to indicate, so Oc. has been 
omitted from my letters of reference, as I must believe he refers to 01.—Trans. 
21 It appears to me more to the point to consider the foramen for the glossopha- 
ryngeal and the posterior border of the petrosal as the extreme anterior boundary of 
the occipital region in the bony Ganoids and Teleostei, and not the foramen for the 
vagus, as Gegenbaur has done for the Selachians. In the fishes examined by us these 
two nerves are intimately related to each other, and in rare cases they may even have 
a common foramen of exit, so that placing them in this or that region would be quite 
arbitrary. Moreover, in the limitation proposed by mo the confines of regions are 
almost without exception defined by the sutures between the bones, and therefore it 
becomes unnecessary to award a bone to different regions. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
The base of the occiput is occupied by the basioccipital (Plate Ir 
Figs. 2 and 3; Plate II, Figs. 4 and 5, Ob.). This bone has the form of 
a mussel-shell, not unlike Cardium or Pecten. Posteriorly it is shaped 
like the centrum of a vertebra, and presents for examination a tolerably 
even and conical excavation, into which the anterior end of the chorda 
enters. The margin of this excavation is connected by stout ligament- 
ous bands to the centrum of the first vertebra, the anterior side of 
which appears slightly convex. Articulating with the lateral margins 
of the basioccipital are the exoccipitals (Plate I, Figs. 1 and 3 01.). 
These two bones, for the greater part of the posterior aspect of the 
primoidal cranium, assist in the formation of the lateral region only to 
a small extent. In large specimens of Amia calva they join together 
in the middle line over the medulla oblongata by means of a suture; in 
immature specimens they are separated throughout their entire extent 
by a strip of cartilage. They form no part of the articulation of the 
neural arch of the first vertebra, but they are separated from it by two 
bony arches, which rise upon the posterior portion of the basioccipital, 
having the form of a vertebral centrum, and which correspond in every 
respect with the neural arch of the vertebra, and shall be termed the 
occipital arches (Plate II, Figs. 4, 5, and 6, Oc. I and Oc. II).22 
The anterior occipital arch is formed by two triangular osseous plate- 
lets, meeting together over the spinal cord, above which a lion-paired ob- 
long bone, directed upwards and backwards, is fastened by ligaments.23 
The posterior arch is similarly fashioned, only both of its parts are 
of an oblong quadrangular shape, and develop on their posterior aspect 
a small articular facet for the arch of the first vertebra. Upon this 
arch is found also a pointed bone, directed upwards and backwards.24 
The pointed bones resting upon the occipital arch are to be considered 
as spinal processes. At the same time, however, I will remark that in- 
asmuch as they are situated in a line with the uppermost interspinous 
bones, which, indeed, no longer support the fins, one can just as well 
count them in with the latter. The boundaries between the fin-rays and 
the interspinous bones in Amia are not strictly defined, and the arrange- 
ment or condition they present us with iu this form furnishes another 
proof that these formations originally had a genetic connection with 
each other. A good drawing of these conditions lias been furnished us 
by Franque in Fig. 2 of his familiar treatise. 
The occipital arches of Amia are not of uncommon occurrence, but are gen- 
erally present either as independent arches, or reduced in various ways, or at- 
22 Reads obg. in original text.—Trans. 
23 So I find the condition in the older specimens. In the yonnger individuals, from 
which the illustration is taken, each half of the occipital arch consists of three sep- 
arate osseous portions—one lower triangular piece, and two upper ones resting upon 
it and situated behind one another. It is not possible to find an explanation for 
this state of things at present. 
24 In the older specimens of Amia the two pointed bones are blended into one osse- 
ous plate. 13 
THE OSTEOLOGY OF AMIA CALVA. 
tached to the hinder extremity of the skull, as in the higher fishes which are 
provided with ossified skulls. 
In Folypterus a free occipital arch has been described by Traquair. 
Frauque has also observed the occipital arches of Amia, as would ap- 
pear from his brief and not entirely lucid description, but their signifi- 
cance appears to have entirely escaped him. Bridge mentions them 
also. Here and there other authors have noticed them, without having, 
up to the present time, placed any weight upon the occurrence of pre- 
cisely the same thing in bony fishes. I have been able also to convince 
myself that the occipital arch is not wanting in Leptidosteus. In this 
Sauroid I find both halves synosteologically joined together, as well as 
with the basioccipital, so that this latter bone appears to form by itself 
the periphery of the occipital foramen. Among the osseous fishes one 
finds in the pike free occipital arches beautifully developed, also in the 
Salmonidae and Olupeidse; but, as shall now be particularly mentioned, 
proof can be furnished that all Teleostei originally possessed occipital 
arches. 
Over the occipitale laterale, and connected with it at one small point, 
is found the conical exoccipital (Plate I, Fig. 1, Ex.). It constitutes 
the boundary to the entrance of the temporal fossa, mesiad, and is 
partly covered on its superior surface by the posterior margin of the 
parietal. 
The posterior lateral angle of the primoidal cranium is occupied by a 
thoroughly developed bone, which I, in concurrence with Bridge, can 
only take to be the intercalare (opisthotic) (Plate I, Figs. 1,2, and 3, Jc.). 
It is also a conical bone, which is covered above by the posterior lateral 
angle of the squamosum, and which helps to form the lateral boundary 
of the entrance to the temporal fossa. It does not articulate with the 
exoccipital, but remains separated from it by a strip of cartilage lying 
at the base of the temporal fossa. Posteriorly and beneath it comes 
in contact with the occipitale laterale, and in some individuals also with 
the basioccipital. Below and anteriorly, the intercalare, though a very 
delicate process, meets and unites with a process from the petrosal. 
To the apex of this bone, chiefly projecting posteriorly, the inferior limb 
of the supraclavicular is attached, as already shown, by means of firm 
ligaments. Below, the intercalare meets with the cartilage of the pri- 
moidal cranium, at which point something of a protuberance is developed. 
It is known that in most osseous fishes the intercalare is wanting, 
and in the minority, where it still exists, it is feebly developed, with 
the exception of the family Gadidae.25 
Yet a comparison of the condition in Amia with that of the Gadidce 
leaves not a shadow of a doubt that the bone just described is really 
the intercalare, inasmuch as this very bone in the Gadidae possesses 
25 Compare the careful description of the intercalare of the Gadid® by Vrolick, 
“ Studien iiber die Verkudcherung und die Knochen des Schadels der TeleosteiNiederland. 
Archiv. f. Zoologie, Bd. 1, 1873. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
precisely the same topographical relations to neighboring ossifications 
of the skull, to the suprascapula, and to the foramen for the exit of 
the vagus and the glossopharyngeal. 
The nerve situated most anteriorly in the occipital region is the 
glossopharyngeal. Its foramen of exit is found where the intercalare, 
the petrosal, and the cartilaginous portion of the primoidal cranium 
come together, and below and between the basioccipital and petrosal 
(Plate I, Figs. 2 and 3, gph.). Immediately after its exit from the fora- 
men the glossopharyngeal divides into its two well-known branches, 
the distribution of which is of no interest in the present connection. 
Thoroughly separated from the glossopharyngeal foramen we find 
the foramen for the vagus is so located in the suture between the inter- 
calare and the occipitale la terale that its periphery is formed by these two 
bones (Plate I, Figs. 2 and 3, r.26). The nerve itself exhibits essentially 
the same behavior after its exit as in the Teleostei. 
Wliile yet within the brain-case the vagus gives off a very minute 
branch, which, ascending upwards, perforates the cartilaginous skull- 
cover beneath the parietal, into which it enters, probably to supply its 
mucus canal. I should not have mentioned this little branch at all if 
the so called ramus lateralis nervi trigemini, which is known to receive 
fibers from the trigeminus and from the vagus, did not quit the cranium 
at the same locality in many of the Teleostei. That this nerve in Amia 
also receives fibers through its anastomosis with cranial nerves that 
arise more anteriorly I have once been able to confirm, but, in conse- 
quence of the indifferent manner in which the specimen I examined had 
been preserved, it was impossible to ascertain from which nerve this 
anastomosis proceeded. While the occipital region of the Selachians27 
arrives at its posterior limits with the vagus, in fishes provided with 
ossified skulls several nerves of the occipital group, and of a character 
identical with the spinal nerves, are constantly to be found between the 
vagus and the first spinal nerve. 
Amia, possessing the largest number hitherto observed of occipital 
nerves, furnishes us with three such for our consideration. The most 
anterior of these leaves the brain-case at a minute foramen in the occip- 
itale laterale, and situated near its posterior border (Plate II, Fig. 4, oc 
I). It is of a smaller caliber than the two following, and also differs from 
them in that it only arises from the spinal cord by means of an anterior 
root. The nerve next in order arises by both an anterior and posterior 
root, between the hinder border of the occipitale laterale and the ante- 
rior occipital arch (Plate II, Fig. 5, oc II). Immediately after their 
exit these two roots unite in a common trunk, and in so doing carry out 
the character of a spinal nerve (Plate II, Fig. 5, oc III). The first 
spinal nerve in Amia quits the neural canal between the posterior occi- 
2fi Marked vg. in original text.—Trans. 
27 As a matter of course only sucli Selackians are here taken into consideration whose 
crania are sharply defined from the vertebral column. 15 
THE OSTEOLOGY OF AMIA CALVA. 
pital arch and the neural arch of the first vertebra, presenting us with 
nothing of particular note. 
The three occipital nerves, together forming a group, run downwards 
in front of the shoulder-girdle, to finally ramify, and—probably together 
with the branch of the first spinal nerve, agreeing in this respect with 
the corresponding nerves in the Teleostei—to supply the muscles lying 
between the shoulder-girdle and the mandible. This I could not estab- 
lish with certainty, for the reason that the specimen used by me for the 
examination of the nerves had already served for a dissection of the 
heart and great vessels. To complete the subject, a canal must yet be 
mentioned, the function of which I have been absolutely unable to dis- 
cover. It commences on the lateral aspect of the bassioccipital, and 
on that portion of this bone which so much resembles a vertebra; it 
takes a course towards the median plane, turns at a right angle, and 
terminates at the inferior surface of the bone, between the posterior 
wings of the parasphenoid. This terminal opening is in close juxta- 
position with the same opening of the canal of the opposite side, but no 
communication exists between them nor with the cavum cranii. The 
contents of this canal I found to be fibrous connective tissue and thin- 
walled vessels of some caliber (Plate I, Figs. 2 and 3, cb.). 
The fact that free and independent neural arches are found upon the basi- 
occipital, from between which emerge nerves of a structure like true spinal 
nerves, is of fundamental importance in the determination of skulls of the 
higher fishes, and admits of no other explanation than that which applies 
to the primoidal cranium, the best example of which we find in the Se- 
lachians, where we observe anchylosed together a still greater number of 
vertebrae, with the nerves that pertain to them making their proper exits. 
A question still more difficult of determination is to define the num- 
ber of vertebrae that enter into the composition of the cranium. In Amia, 
which for this purpose—of all the fishes with osseous skulls examined 
by me—possesses the best example of this primitive condition, I believe I 
am enabled to recognize the elements of three vertebrae. That the two 
occipital arches, with the nerves that pertain to them, represent the re- 
mains of what were originally distinct vertebrae, no reasonable doubt 
can exist; and the only question is whether we are to consider the first 
occipital nerve, which is ver3* feebly developed and without a posterior 
[dorsal] root, as a rudimentary spinal nerve, or whether another inter- 
pretation is aidmissible. 
If tlie first occipital nerve is not to be considered as a rudimentary 
spinal nerve, one can see in it—since it is absolutely inconceivable, to 
have a generation of new nerves in the higher animals—but a branch of 
one of the two neighboring nerves, namely, of the vagus or of the sec- 
ond occipital nerve, that has branched and become independent. Now, 
the distribution of the first occipital nerve is such, that one cannot for 
an instant take it to be a branch of the vagus at all, and therefore the 
only possibility remains that it could belong to the second occipital REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
16 
nerve. Such a thing as the branches of nerves eventually becoming 
mew and independent nerves does occur in fishes, and I would invite 
attention to the condition seen in the spinal nerves in the Gadidae,28 and 
to the condition seen in the ramus palatinus nervi facialis in many 
bony fishes. There are two factors to be taken into consideration that 
enter into such a divisional process. The first of these is that distal 
regions supplied by the nerve may grow apart, and become further and 
further separated from each other; and the second is, that the tendency 
of each nerve is to take a direct course to the part it supplies. Both of 
these conditions would eventually bring about a division of a nerve to its 
very origin. Therefore this division must begin at the distal end of the 
nerve, and, gradually progressing, must extend finally to the point of 
origin in the central nervous system. 
Precisely the opposite condition is found in the first occipital nerve; 
distally it is united with the second occipital nerve, it being but par- 
tially separated from it. Therefore the onlj justifiable conclusion we 
have left us to adopt is that this nerve must be considered as a discrete 
spinal nerve, the survivor of a retrogressive process, and so in Amia 
we must assume that at least three vertebras have merged into the 
cranium. 
I‘ have yet to invite more careful attention to a condition not remarked 
upon by me before. Upon closer scrutiny of the occipitale laterale one 
sees that the hindermost part of this bone, where it meets the anterior 
occipital arch, is thickened and consequently well defined from the 
other bones. The anterior border of this thickened strip is in immediate 
relation with the minute foramen of exit of the first occipital nerve, and 
consequently this thickened portion of the bone exactly corresponds in 
form as well as in its site to a third anterior semi-occipital arch that 
has merged into the occipitalia lateralia. Now that the proof lias been 
furnished that vertebrae, originally separate, have blended with the 
skull, an explanation can be given for certain points for examination 
that are to be found upon the inferior aspect of the basioccipital, which 
have not been alluded to by me before, because their significance would 
not have been understood. 
Between the two posterior limbs of the parasphenoid, immediately 
behind the two lower exits of the vascular canals described above, 
that pass through the basioccipital, one finds two small pieces of car- 
tilage, quite superficially placed upon the surface of the bone. (Plate I, 
Pig. 2, x.) On viewing the vertebral column of this fish from beueath, 
one can satisfy himself that very similar pieces of cartilage are upon 
each vertebral centrum; indeed, in younger individuals these cartilages 
penetrate deeply into the substance of the centra, while in the older 
specimens only very thin cartilaginous pieces can be recognized rest- 
ing superficially on the vertebrae. 
28 Stanniu8, Das peripherische Nervensystem der Fische, pag. 119. THE OSTEOLOGY OF AMIA CALVA, 
Without going any further into an explanation of these cartilaginous 
formations, which could only be done by a careful comparison of the 
vertebral column of Amia with that of other fishes, I feel called upon 
to invite attention to the remarkable—even in details—similarity of 
the posterior portion of the basioccipital to the centrum of a vertebra. 
To make a comprehensive statement, the occiput of Amia calva re- 
veals the elements of three vertebrae, which are co-ossified with it, 
and whose individual independence becomes less and less marked from 
behind forwards. The centrum of the hindmost vertebra, as well as 
the centra of the other two, is co-ossified with the basioccipital; it is, 
however, only in the posterior portion of this bone that the evident 
likeness to the centrum of a vertebra can be recognized. The neural 
arch of this vertebra cannot be distinguished from the neural arch of 
a trunk-vertebra, and it possesses also a well-formed spinous process; 
the corresponding nerve is stamped with all the characteristics of a 
typical spinal nerve. The middle vertebra, absorbed as it is by the 
cranium, is quite similarly formed, only that its neural arch has be- 
come broader and intimately blended with the cranium. The trans- 
formation and co-ossification of the anterior vertebra is the most com 
plete. Both halves of its neural arch are blended with the oeeipitalk 
lateralia, and the nerve corresponding to it arises simply as a feeble 
anterior root [ventral]. This rudimentary nerve is really the only safe 
indication of the existence of this anterior vertebra, which has in other 
respects been completely appropriated by the skull; and should one 
imagine that this nerve was formed through a retrogressive process, or 
became blended with the occipital nerve, then nothing would remain 
to give us the slightest hint as to the original existence of this anterior 
vertebra. This is of importance in so far as it gives rise to the possi- 
bility that beyond this vertebra, the existence of which is still to be seen 
through its last faint traces, there existed other ones, which, however, 
have become thoroughly appropriated by the cranium so as not to be 
any longer distinguishable. 
The number which I have indicated, then—that of three vertebrae co- 
ossified with the skull—can therefore only be the fewest of these seg- 
ments to be recognized. The view that the original number of these 
vertebrae was greater is by no means to be precluded. 
It is hardly worth while mentioning that the facts just discussed by 
me have nothing whatever to do with the question of the composition 
of the primoidal cranium out of like constituents—the so-called verte- 
bral theory of the skull. The formation of the primoidal cranium in 
the Selachii—and maybe, too, in the Cyclostomata—has already been 
perfectly defined 5 and setting the question entirely aside as to whether 
any or how many metameres were contained in those skulls, my only 
aim was to establish that between the Selachian skull and that of the 
higher fishes no complete homology exists. The cranium of the higher 
fishes corresponds to the cranium of the Selachii, plus several (at least 
three) of the anterior vertebrae of the column. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
I would also expressly state that the proof just given only applies to 
the higher fishes, and that every attempt to assume the same condition 
for the higher organized vertebrate animals also must be premature at 
lenst. I would not have mentioned this particularly if attempts had 
not been made recently to show that the atlas of the Amniota is eo-ossi- 
fied with the cranium in Amphibia. 
Stohr29 first made the interesting discovery that the so-called odon- 
toid process of the Amphibia is nothing more than the notochord be- 
coming cartilaginous, and subsequently developing as an ossified pro- 
cess from the first vertebra. Upon this discovery30 Wiederscheim has 
made the assertion, for which there is no foundation, that the atlas of the 
Amniota is to be looked for in the occipital part of the skull of the Am- 
phibia, and that in consequence of this the first vertebra in these forms 
corresponds to the axis. 
After considering that the arrangement of tfie nerves in the occipital 
region, and of the first spinal nerves in the Selachians and Amphibia, 
at least in the Urodela, is identical; that in both, the vagus is the last 
nerve given off by the brain; further, that the entire occipital region 
in the Amphibia appears extraordinarily rudimentary, weighty reasons 
arose in my mind discrediting the idea that we find in the Amphibia 
the skull appropriating one of the vertebra, and I rather believed that 
a complete homology of the skulls in the Amphibia and Selachians must 
be accepted. Wiederscheim’s view has its origin in the one-sided com- 
parison of the conditions of organization in the Amphibia with that in 
the Amniota. Existing Amphibia, so far as their crania go, form a very 
restricted group by themselves, their structure permitting certain com- 
parisons to be made down the scale toward the Dipnoi and Selachians, 
but not upward toward the Amniota. Consequently, if one foregoes a 
direct comparison of the skull of the Amphibia with that of the Am- 
niota, a phylogenetic interpretation of the ontogenetic facts discovered 
by Stohr would not be difficult. In all fishes, particularly the Sela- 
chians, a conically-pointed piece of the chorda extends into the occipi- 
tal region of the skull, and one need only imagine that this notochord 
be transformed to cartilage, and afterwards—developed from the first 
vertebra—to ossify, in order to arrive at exactly the same conditions as 
they exist in Amphibia. 
Then, to be sure, the odontoid process of the Apiphibia is not homolo- 
gous with the structure bearing the same name in the Amniota, but only 
presents an analogous formation; yet the supposition of homology even 
does not seem to me at all probable, inasmuch as it can be easily shown 
29 Ph. Stohr, History of the Development of the Skulls of Urodela. Zeitschrift f. 
wis8. Zoolog., Bd. 33. 1880. 
30 Wiederscheim, Comparative Anatomy of the Vertebrate Animals, page 60. It is 
not uninteresting that Albrecht (Zoolog. Anzeiger, 1880, Nos. 64 and 65), upon this 
same report, draws the opposite conclusion, and interprets the first vertebra of the 
Amphibia as his imaginary “pro-atlas” lying beyond the atlas, and the odontoid pro- 
cess of the Amphibia as the basioccipital separated from the cranium. THE OSTEOLOGY OF AMIA CALYA. 
that the formation of the odontoid process out of the body of the atlas 
in the Amuiota only begins among the reptiles.31 In higher fishes it is 
very generally found that the anterior aspect of the first vertebra is not 
excavated, but slightly convex. Now, though it seems to me to be im- 
probable that the conditions in Amphibia can be traced directly to these 
structures in fishes, yet here is a state of things that can be considered 
parallel with that of the Amphibia. 
An explanation for the singular fact that in the higher fishes inde- 
pendent vertebra are co-ossified with the occiput is not difficult to find, 
and I believe the reason for this condition is to be found iu the w ay 
and method in which the parasphenoid makes its appearance. 
It has been fully and conclusively shown by Hertwig that teeth can 
be discovered upon all the bones of the buccal cavity, which arise from 
these osseous plates through sockets in their substance, and that the para- 
sphenoid forms no exception to this rule, although teeth are found upon it 
far more seldom than on the other bones of the mouth. If we now know 
that the appearance of teeth in the Selachians is not confined to the 
cavity of the mouth, but that they also extend upon the mucous mem- 
brane of the fore-gut, as far as the gill slits, thus reaching far below the 
anterior extremity of the vertebral column, then the supposition will not 
be startling that the parasphenoid originally did not confine itself to 
the basis cranii, but extended far behind it upon the vertebral column. 
Iu fact, we meet with the parasphenoid occupying this very position 
in those tislies in which bone first begins to appear, in the cartilaginous 
Ganoids, and in the Dipnoi. As already known, the parasphenoid of 
Stolirs does dot confine itself to the base of the true skull, but extends 
backwards to be applied to the inferior surface of the centra of about 
7 or 8 vertebrae. According to Wiederscheim this is the arrangement 
in Poly [items, and Gunther tells us that it also occurs in Ceratodus, only 
in these fishes the number of vertebrae covered by the parasphenoid is 
fewer. This also must have been the state of things in the direct ances- 
try of the existing bony Ganoids and Teleostei. Now, after the para- 
sphenoid had ceased to be a tooth-bearing bone of the cavity of the 
mouth, a curtailment from behind took place, and at the same time a 
reduction in number and consolidation of the vertebrae resting upon this 
bone, which was already firmly connected with the cranium, set in, to 
replace the latter, a transformation the last traces of which can still be 
seen in bony Ganoids and Teleosteans. 
The region of the labyrinth32 is bounded posteriorly by the foramen 
31 Gegenbaur, Grundziige der vergl. Anatomic, 2 Aufl., page 615. 
32 Labyrinth region, the term here used, applies more particularly to that space as 
seen in the Teleostei and bony Ganoids, which, by the way, it does not entirely in- 
clude, as the labyrinth in these fishes generally extends beyond the confines given ; 
moreover, all the bones enumerated by me as belonging to the occipital region may, 
under certain circumstances, serve for the inclosure of parts of this area. So I have 
retained the term simply to avoid a new name. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
20 
for the exit of the glossopharyngeus; anteriorly by the postorbital pro- 
cess and the posterior circumference of the orbit. 
It forms the greater part of the lateral wall of the skull situated be- 
hind the orbits and includes the ossified petrosal and postfrontal. 
The petrosal (Plate I, Figs. 2 and 3, Pe) is nearly circular in form, be- 
ing connected behind and above by a small part of its periphery to the 
intercalare in a serrate suture. 
It is separated from the surrounding bones by broad areas of carti- 
lage, from the basioccipital posteriorly, the squamosal laterally and 
above, the postfrontal above and anteriorly, from the alisphenoid ante- 
riorly, and from the petrosal of the opposite side by a mesial band of 
the same material. 
Above the petrosal we find the long, flat, and longitudinally placed 
facet of articulation for the hyomandibular (Plate I, Figs. 2 and 3 km.). 
This facet is entirely in cartilage, with the exception of the postero- 
superior angle, which is slightly overlapped by a thin piece of the squa- 
mosal. 
Anteriorly and above the petrosal lies the ossified postorbital process 
—the postfrontal (Plate I, Figs. 2 and 3, Psf.). This bone has the form 
of a triangular pyramid, whose apex is directed laterally and upward. 
The superior aspect of this bone, which is stamped with all the characters 
of a dermal bone, has already been thoroughly described ; of the two re- 
maining sides, one faces outward and the other assists in forming the 
hinder part of the upper margin of the orbit. The ossification of the 
postfrontal does not reach through the entire thickness of the lateral 
cartilaginous skull wall, but remains separated from the brain cavity at 
all points by cartilage. Now, at the dividing line between the bone and 
the cartilage there lies a canal that commences at the lower margin of 
the bone at the side of the skull and makes its exit at the anterior angle 
of the temporal fossa. So far as I could satisfy myself, it contains ves- 
sels intended for the soft parts contained in the temporal fossa. This 
canal has no greater morphological significance, and I only mention it 
for the sake of making my description complete. Two openings are 
formed near the anterior margin of the petrosal; the upper and larger 
one is for the facial nerve and jugular vein (Plate I, Figs. 2 and 3 fa.), 
the smaller and lower one for the carotid (Plate I, Fig. 3 ea.). While 
still in the brain case the facial nerve gives off a branch which, running 
forward, enters the orbit at the posterior margin of the fenestra—to be 
spoken of further on—thence traversing the lower lateral margin of 
this cavity, to be distributed to the mucous membrane of the mouth. 
This branch of the facial, which universally occurs in the Teleosteans, 
has always been referred to as the homologue of the ramus palatinus 
of the Selachians. If one considers that the ramus palatinus of the 
Selachians always arises extracranial from the facial, and from this ori- 
gin runs anteriorly, while the nerve bearing the same name in Amia and 
bony fishes has an intracranial origin, the question of their homology THE OSTEOLOGY OF AMIA CALVA. 
becomes dubious. To render this homological comparison safe, we must 
have the positive proof, now missing, that this branch penetrates from 
the outer side of the skull to the inner in this series of fishes. The 
further distribution of the facial nerve after it quits the brain case is 
of no further interest in the present connection. 
The orbital region is very definitely marked off. Its posterior bound- 
ary has already been alluded to; anteriorly the antiorbital process, with 
its ossification, the prefrontal, divides it from the nasal region. In Amia 
the orbits are tolerably fiat and oval depressions, separated from one 
another in the median plane by an antero-projecting process of the 
cavum cranii (Figs. 9 and 10); there is not a trace present in Amia of a 
bony or membranous interorbital septum, as we find in so many of 
the Teleostei. 
The roof of the orbit is formed only to a limited extent by a carti- 
laginous, laterally-projecting ledge of the primoidal cranium, w'hich 
one may consider as the last remnant of a cartilaginous orbital roof 
(Figs. 2 and 3), the greater part of this roof being furnished by the 
troutal bone. An orbital base is indicated by a feebly developed, wing- 
like ledge projecting from the basis cranii, which is in contact with the 
parasphenoid beneath (Figs. 9 and 10). 
The anterior third of the wall of the orbit is entirely cartilaginous,33 
while the posterior two-thirds are in part occupied by two ossifications. 
There is a large foramen found in the posterior part of the orbit, bounded 
above, behind, and in front by serrate edges of bone and below' by car- 
tilage, w'hich opens into the brain case (Plate I, Figs. 2 and 3, Op.). 
Posteriorly through this opening passes the optic and several other 
nerves out of the cranium, and through it the muscles of the eye reach 
the skull; anteriorly it is closed by a strong fibrous membrane. In 
many of the skulls of the Selachians one can see a feuestratiou of the 
lateral wall of the cranium, which is an extension of the foramen opticus, 
and it does not appear very improbable to me that the foramen I have 
just described in Amia is to be regarded as such a foramen opticus, 
much enlarged. At the boundary line between the labyrinth and 
orbital regions the cartilaginous base of the cranium is further pierced 
by a small foramen, which is covered by the parasphenoid, and which is 
only disclosed l)> removing that bone (Plate I, Fig. 3, fli.). This foramen 
in its position corresponds to the liypoplysis—to be described further 
on—and is to be compared in many bony fishes to that lengthened cleft 
at the base of the fossa for the muscles of the eye, which is closed by 
the parasphenoid. 
The alispJienoid, constituting as it does the posterior ossification of 
the orbital region, is of a circular form, with a section cut from it below 
33 In a large specimen of Amia I saw the lateral, as well as the side toward the 
median plane—facing towards the cavura cranii—of this anterior orbital cartilage 
covered by a thin snperticial layer of a brownish color, which at first sight looked like 
a very thin lamella of bone. A microscopical examination showed here that we had 
to deal with a calcification of the superficial layer of cartilage. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
and anteriorly. This missing section is the foramen just described, and 
its outline depends upon it (Plate I, Figs. 2 and 3, As.). 
Near its posterior margin the alisphenoid is perforated by a large cir- 
cular foramen, intended for the second and third branch of the trigemi- 
nal. In large specimens of Amia the alisphenoid articulates above and 
posteriorly with the postfrontal; in younger individuals it is separated 
from the latter by a small zone of cartilage. Above the optic foramen, 
anteriorly, it is to a small extent suturally united with the orbitosphe- 
noid. 
Beyond the alisphenoid is found the orMtosphenoid, circular in out- 
line and pierced behind and below for the optic foramen, of which 
nothing further will be remarked (Plate I, Figs. 2 and 3, Os.). It seems 
to me that at this point it would not be uninteresting to call attention 
to the circular form of so many of the ossifications of the primoidal 
cranium of Amia. 
These forms are due to the fact that the centers of ossification start 
free in the cartilaginous matrix, and in their unhindered growth, which 
has been a proportionate increase of margin in all directions, they have 
but at a few places only been checked by contact with neighboring ossi- 
fications. In this respect, too, Amia has been preserved in a primitive 
condition, as compared with the Teleostei, in which the corresponding 
bones, owing to the fact of their contact at most points with their neigh- 
bors, exhibit a great irregularity of form. 
The first branch of the trigeminus passes through the wall, of the 
primoidal cranium at about the height of the anterior margin of the 
postfrontal, runs obliquely forwards and outwards, and quits the ali- 
sphenoid just above the large foramen for the second and third branch 
of the same nerve (Plate II, Fig. 6, tr.34). 
During its course within the wall of the skull it gives off* several mi- 
nute branches, which ascend upward in the cartilage and pass to the 
mucus canals of the bones of the skull cover. In the orbits these 
branches are two in number, and lie parallel to each other; just be- 
neath the “cover;” they pass forward to reach the nasal depression to 
which they are distributed, and in doing so pass between the cartilag- 
inous cover of the primoidal cranium and the frontal. 
During its entire course through the orbit it gives off minute ascend- 
ing branches, which in part perforate the cartilaginous roof, described 
above as the remains of the vault of the orbit, which is composed of this 
material, while another branch passes to be distributed to the mucus 
canals of the frontal bone. 
The second and third branches of the trigeminus nerve pass from the 
skull cavity through the foramen in the alisphenoid already referred to, 
and are distributed in precisely the same manner as they are in the 
Teleosteans (Plate II, Figs. 4 and 5, Tr.). 
3*Tr. in the figure.—Trans. THE OSTEOLOGY OF AMIA CALVA. 
The oculomotorius and the troclilearis pass out through the large 
posterior foramen of the orbital region, at its posterior margin, the first- 
mentioned nerve above and the second beneath it. 
Between these two nerves lies the group of straight eye muscles, of 
which the rectus externus is contained to some degree inside the cranium, 
and gives rise to the development of an eye-muscle canal. 
Just anterior to the eye muscles, yet partly lying between them, we 
find the optic nerve, which in Amia is but feebly developed, owing to 
the small size of the eye. The ophthalmic artery, quite large in Amia, 
passes also into the bulbus with the optic. Between the last-named 
structures lies a strong fibrous cord, which arises at the posterior lower 
angle of the orbital cavity, to be inserted near the place of entrance 
of the optic on the bulbus. This cord corresponds in every respect to 
the eye supports in the Selachii. The two oblique muscles are inserted 
into the anterior angle of the orbit. 
The nasal region of the primoidal skull of Amia is bounded behind 
by the antorbital processes, and has the shape of a triangular plate, 
bearing a superior median crest. With the exception of two small ossi- 
fications, the entire region is cartilaginous. On the inferior aspect of 
this region, situated mesially and in front of the antorbital processes, 
lie two oblong cartilaginous articulating facets for the anterior extrem- 
ity of the palatine arch; the distal end of these touches the ossitied 
part of this region, the septomaxillare (Plate I, Fig. 3, and Plate II, 
Fig. 5, Smx.). This is an osseous center that extends from the lower 
margin of the foramen for the nasal nerve to the lateral margin of the 
prenasal cartilage, and with which the maxillary is movably articulated 
at the latter place. The greater part of this small bone is covered above 
by the intermaxillary, and only becomes visible after this bone is removed. 
This bone has been declared identical by Bridge with the ossification 
at the base of the nasal capsule of the frog (the septomaxillare); and 
although I consider the homology thus assumed as at least improbable, 
still I did not introduce a new name. 
It would appear to me more correct if Bridge had compared the two 
small ossifications known to us, which occur at the extremity of the 
cartilaginous rostrum of the Pike, with the septomaxillary of Amia, 
with which, indeed, they correspond in position as well as in their re- 
lation to the neighboring parts of the skeleton. 
The cranial cavity is egg-shaped, with the apex directed forwards; that 
about the labyrinth region presents two niclie-like depressions, for the 
concealment of the labyrinth, that are sharply defined as we proceed 
backwards towards the hinder extremity of the brain case. In Amia, as 
among the Selachii and Ganoids, this depression extends from the fora- 
men magnum to the nasal fossae. Not all of the ossifications of the pri- 
moidal cranium that are to be seen on the outer aspect are to be ob- 
served on the inner walls of the brain case or in the connecting spaces of 
the labyrinth; on the contrary, quite a number of them do not reach REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
through the entire thickness of the skull wall, and therefore remain sep- 
arated from the cranial cavity by a layer of cartilage. 
The exoccipital, the intercalare, and the post- and prefrontal are found 
to be in this condition. 
It is hardly worth while mentioning that the squamosal also belongs 
to this category, applied as it is, in most fishes, to bound a portion of 
the outer arch; a like condition obtains in Amia, where, as has been 
fully discussed, it retains the character of a cover-bone throughout 
life. 
Within the cavum cranii the anterior part of the occipital region is 
very sharply defined by an elevation directed anteriorly and towards the 
median line, composed partly of cartilage and partly of membrane, 
which runs along the lateral wall from above downwards, forming the 
posterior wall of the niche of the labyrinth. The base of this region is 
formed by the basioccipital, by the lateral walls, and for the greater 
part also by the cover-bone of the occipitalia lateralia; the adjoining 
portion of the spinal canal, which is covered by the occipital arch pos- 
teriorly, does not lie in the same plane with the base of the brain cavity, 
but is found higher up on the posterior wall of the skull, so there re- 
mains a fossa in this locality, which terminates blindly behind and 
below, over which the medulla oblongata and the anterior end of the 
spinal marrow pass. This depression is filled in with the now recog- 
nized interdural lymphatic fat tissue,35 most extensively found in the 
Teleosteans, and becomes interesting to us for the reason that in the 
family of Cliaraeinides, Cyprinoides, the Shads andGymnotides, it is this 
very depression that is partitioned off from the rest of the skull cavity 
by’ the crests of the occipitalia lateralia, which meet mesially, and is 
utilized for the formation of the “atrium sinus imparis,” which is con- 
nected with the swim-bladder by means of the apparatus of Weber. 
The broad foramen for the vagus is situated at the anterior margin of 
the occipitale laterale. The anterior border of the labyrinth region 
within the brain case is formed by the anterior margin of the petrosal 
which does not join with the anterior bounding ledge of the labyrinth 
niche, but runs a little before it. The exceedingly’ complicated struct- 
ure of the labyrinth niche, with the canals for the arches, is for the 
most part cartilaginous; its lateral wall is only formed by the petrosal 
below and anteriorly. The labyrinth is divided by a medial and pro- 
jecting cartilaginous elevation, running anteroposteriorly and from 
above downwards into two fossa), the smaller one being situated an- 
teriorly and above, the larger one posteriorly and below; the former 
contains the greater part of the utriculus, the latter is intended for the 
sacculus with the reeessus cochlearis. The recess for the saceulus forms, 
as I have already had occasion to state, quite a prominence on the 
lateral wall of the skull, which is to be regarded as the commencement 
36 Usually this fat tissue of lishes is taken for the arachnoid in these forms. I have 
reserved my full reasou for a dissenting view for a later work. THE OSTEOLOGY OF AMIA CALVA. 
of the bulla acustica, so extensively and in some cases excessively36 de- 
veloped in the Teleostei. I wish to state once more particularly that 
the canals intended for the arches, and bounded everywhere by cartilage, 
join with the labyrinth niche. 
The anterior semicircular canal begins at the anterior upper portion 
of the utricnlus inlet, courses laterally forwards and upwards, makes 
a turn in the vicinity of the postfrontal, running close beneath the 
cartilaginous skull cover, to be partly seen through it posteriorly and 
towards the median line, and finally terminates in the cavum cranii in an 
opening above the vestibule of the labyrinth (labyrinth niche). The 
outer semicircular canal takes its origin from the posterior portion of 
the utricnlus, courses laterally and backwards, is barely seen just be- 
neath the hyomandibular facet through the cartilaginous side wall of 
the skull, then proceeds backwards towards the median plane to find 
its exit, in common with the origin of the posterior canal, on the hinder 
boundary of the saeculus. During its course the outer canal approaches 
tolerably close to the iutercalare. The posterior semicircular canal be- 
gins, as already stated, at the posterior margin of the saeculus, courses 
laterally backwards and upwards, comes almost in immediate contact 
with the exoccipital, then turns towards the median plane, forward, 
and makes its exit just above the vestibule of the labyrinth. 
The description of the membranous labyrinth can be briefly presented. 
So far as I could convince myself from the specimens that were at my 
command, and really which were hardly suitable for a critical examina- 
tion, it perfectly corresponds in its general structure with the labyrinth 
of the Teleostei, as we have learned from the admirable investigations 
made by Hasse.37 It is described still more in detail by Retzius.38 
The relation of tlie labyrinth to the cavuin cranii in Amia calva shows 
a marked difference when compared with that of the Selachii. While 
in the Selachians the cavity of the labyrinth seems entirely isolated 
from the brain case, there exists in Amia and all other Ganoids and 
Teleosteans a more or less broad communication between these cavities. 
It would hardly be amiss if one would trace the causes of the varying 
size ot the intercommunicating fenestra between the two cavities to 
the entirely disproportionate development and unfolding of the bod}7 of 
the labyrinth in the higher fishes, which has finally led to a stinted 
growth of the medial dividing wall of the same. The acusticus foramen 
has been in all probability the starting point for the fenestration of this 
wall. At least I think we are justified in assuming this from the posi- 
tion of this foramen of the labyrinth in Amia (when it is nothing more 
than the occurrence of absorption of the periphery of the foramen acus- 
36 In the Scopelus and Gonostoma I find a very extraordinary development of the 
bnllm acusticse. 
87 C. Hasse, Avatomische Studien, Th. X. Das Gehororgan der Fische. Leipzig, 1873. 
38 G. Retzius, Das Gehororgan der Wirbelthiere [Vertebrates]. Th. 1. Fische and 
Amphibicn, page 35. Stockholm, 1881. REPOET OE COMMISSIONER OF FISII AND FISHERIES. 
ticus) as well as the fact that fenestrations in the skeleton in general 
are predisposed to proceed from the peripheries of the nerve foramina; 
as examples of which I would invite attention to the various foramiual 
perforations that occur at the points of exit of the cranial nerves in Se- 
lachians. 
It is my wish now to make especial mention of certain important 
differences that exist between the labyrinth in Amia and that cavity 
in the Teleosteans. The more complete development of the labyrinth in 
osseous fishes has finally led to the belief that the still distinctly marked 
elevations that bound the labyrinth niches in Amia, where they occur 
in a rudimentary condition or are altogether absent, have resulted in a 
mergence of the cavity of the vestibule into the general cavity of the 
brain case, and that the labyrinth has really moved further backwards 
from its original position, appropriating parts that belonged to the 
occipital region, for its concealment. Besides, in the Teleostei the an- 
terior arch has through a reduction in size of the broad cartilaginous 
strips, which in Amia separates it from the skull cavity, very frequently 
come to lie in the latter. 
Finally, an important difference is seen in the fact that the almost 
entirely cartilaginous border of the labyrinth has in the Teleosteans 
been replaced for the greater part by a bony one. Underneath and 
behind the foramen for the facial, the petrosal throws off a horizontal 
lamella of bone, which in the middle line joins with the corresponding 
lamella of the opposite side, and forms the roof of a part of the cavum 
cranii that is closed posteriorly. It is the hindmost of the osseous 
part of the recess for the eye muscles, which is largely membranous in 
Ami a, and of which an accurate description will be given further on. 
While the limits of the separate regions of the skull are but feebly 
defined upon the skull-cover, quite a sharp definition takes place be- 
tween the labyrinth and the orbital regions in the interior of the skull 
on its cover; this is through the means of a feebly-marked ledge, ex- 
tending from one postorbital process to the other, and directed down- 
wards towards thecavum cranii; here its lower edge meets the ascend- 
ing epiphysis coming from below. This epiphyseal ledge of the skull- 
cover is constantly found in all Teleosteans, and represents in some 
individual cases the only remaining portion of the original cover of the 
primoidal skull. 
The question which considers the channels through which the sound- 
waves of the surrounding medium reach the labyrinth in fishes has 
never, up to the present, been the subject of an exhaustive discussion. 
And yet the question deserves to be investigated, because quite a 
number of peculiar formations upon the skulls of fishes will become 
intelligible only after we have become acquainted with the nature of 
the sound-conducting channels. It does not demand any particular 
mention—inasmuch as an experiment is naturally out of the question— 
that the solution of this matter can only be brought about by critical THE OSTEOLOGY OF AMIA GALYA. 
investigations of the topographical relations of the labyrinth region in 
the skulls of fishes, and the determination of the sound-conducting 
channels according to pureiy physical principles. The prevailing idea 
at present is that, in fishes generally, no special channels for the con- 
duction of sounds have been differentiated; that, on the contrary, an 
entirely evenly-proportioned conduction takes place through the bones 
of the skull, and above all through its cover-bones. Specialized auxil- 
iary apparatus of the ear, intended for the conduction of the sound- 
waves to the labyrinth, with the least possible loss, are said to appear 
first in the class Amphibia ; this is positively erroneous. A superficial 
review of the majority of fishes demonstrates the improbability of this 
assumption. In the vast majority of fishes the bones of the cranium at 
no place enter into contact with the surrounding medium, but are sepa- 
rated from it by extraordinarily poor sound-conductors, by a thick 
sw'ardy skin, and frequently even by powerful layers of muscles, so 
that the conduction of the sound-waves directly through the bones of 
the head can be counted on in a comparatively very small number of 
fishes only, as in those whose heads are covered by naked bone-shields. 
The possibility that it takes place through a general conduction on the 
part of the bones must be absolutely set aside for the vast majority of 
fishes, and we will have to look about us for other channels of conduc- 
tion. 
Such a channel has been found for us by Hasse39 in the Clupeidse. He 
found that that portion of the auditory capsule,'which bounds the sac- 
culus laterally, forms the inner wall of the gill cavity, and so enables 
the sound-waves to infringe upon the sacculus through this space. These 
observations are correct, only that Hasse has erred in that he regards 
the intimate relations of the labyrinth to the gill cavity as confined to 
the Clupeidm, whereas it occurs in the majority of osseous fishes. In a 
large number of these latter, representatives of the most widely sepa- 
rated families, I found almost without exception that the anterior supe- 
rior apical recess of the gill cavity lies in close juxtaposition with the 
labyrinth region of the skull, consequently at this point the water pres- 
ent in the gill cavity is only separated from the thin, lateral osseous or 
cartilaginous wall of the labyrinth by a thin mucous membrane. In 
numerous cases, in which the sacculus with its otoliths is fully devel- 
oped and forms a lateral jutting bulla on the skull, this bulla almost 
without exception projects into the gill cavity, and in many instances 
can be felt from the gill cavity by the finger with great ease. Yet I 
would have it distinctly understood that in most cases it is not the sac- 
culus alone that has this relation to the gill cavity, but that the utricu- 
lus also enjoys a similar relation, and so it is not admissible here to 
39 C. Hasse, Anatomische Studien; Suppl. Die vergleicliende Morphologie das hautigen 
Gehorgangs der Wirbelthiere, 1873, page 53. [C. Hasse, Anatomical Studies; Suppl. 
The comparative morphology of the membranous auditory passage of the vertebrated 
animals, 1873, page 53.] REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
assume, as Basse did, that we are dealing with a sound-conducting 
channel or medium specially intended for the saeculus. At present I 
cannot yet enter upon the details of the relations of the labyrinth to the 
gill cavity in the Teleostei, to which I must refer to special descriptions 
to be published later, uxion the crania of separate families of osseous 
fishes. 
Now that the grounds for the assumption have been demonstrated, 
that in bony fishes the sound-waves for the most part reach the labyrinth 
from the gill cavity, the remaining question presents itself as to how the 
sound-waves get into the gill cavity. There can be no doubt that the gill 
cleft plays an important part here; still I believe I am able to point out 
yet another channel which, according to physical principles, must be even 
better suited for the purpose. I mean the conduit which is presented in 
the bones of the opercular apparatus, especially by the operculum and sub- 
operculum. If one reflects that these bones are thin elastic plates in most 
Teleosteans, which through their broad surface are in contact with the 
water contained in the gill cavity, and covered as they are by a thin 
skin only, and at no time being covered by large masses of soft parts; 
then one must admit that an apparatus, thoroughly suited to the pur- 
pose, here presents itself for the conduction of the sound-waves from 
the outer medium to the body of water in the gill cavity. Should fur- 
ther investigations confirm this supposition, it would establish the state- 
ment formerly made by Geoffroy St. Hilaire who, as we are aware, de- 
clared that the opercular boues were ossicula auditus; to be sure in 
an entirely different sense from what this author meant. Although 
somewhat foreign to the subject of my paper, a comparison of the sound- 
conducting media of the bony fishes with those parts in other verte- 
brated animals, especially the Selachii, is of great interest, because such 
comparisons very well illustrate the position that the Teleosteans hold 
with respect to other vertebrates. 
The common opinion is, that differentiated sound-conducting appa- 
ratuses first made their appearances in the Amphibia, more particularly 
among the Anura. It has already been sufficiently dwelt upon that 
this view is an erroneous one, and that in the majority of bony fishes 
no general conduction of the sound-waves to the labyrinth takes place; 
that, on the contrary, channels have been differentiated of a constant 
character. But osseous fishes are not the forms—in the vertebrate 
series—in which such auxiliary apparatuses to the organ of hearing 
first appear; contrivances for such purposes cau already be demonstrated 
to exist in the Selachians, from which the apparatuses in the bony fishes 
were derived. The credit belongs to Johannes Muller40 for being the 
first to truly recognize and appreciate these conditions in the Selachians; 
40 Yergleichende Anatomie der Myxinoiden. Tlieil III. Das Gefiissystem der Myxinoiden. 
Abhandt. d. Berlin. Akademie d. Wissenscliaflen von Jahre 1843. [Comparative Anatomy 
ofMyxinoids. Part III. The vascularsysfcem of tlie Myxinoids. Treat, of the Berlin 
Academy of Sciences, 1843.] 29 
THE OSTEOLOGY OF AM IA CALYA. 
unfortunately his observations appear to have entirely passed into 
oblivion, at least I have not come across a single allusion to them in 
the writings of the more recent authors. The sound-conducting appa- 
ratus in the Selachians is the hyomandibular cleft. This starts, as we 
know, with a wide opening in the buccal cavity iu a position nearer the 
median plane than the opening of the first gill cleft, and close to it, 
and then courses upwards between the hyomandibular and the palato- 
quadratum, making its exit either in an opening, the aforesaid hyoman- 
dibular cleft, behind and above the eye, or ending blindly beneath the 
skin. During its course this canal lies close to the labyrinth region, 
and in individual cases it even presents special blind diverticles, which 
adhere closely to it. This is the point in Selachians where the labyrinth 
is nearest the surrounding medium, and through this channel the sound- 
waves must reach it the least diminished iu intensity. That they may 
be conducted, too, from the surface of the head, is by no means to be 
set aside—such general transmission, to a limited extent even taking 
place in man through parts of the skeleton of the head—yet the idea 
of such a conduction in the Selachians, if the parts concerned are investi- 
gated according to physical principles, must be utterly abandoned, 
when we come to compare this with the part played as a conductor by 
the hyomandibular cleft [speitzloch canalJ. The sound-waves to only 
a limited degree can enter the hyomandibular cleft from the cavity of 
the mouth, and will at least in cases where there is a wide, open, 
external cleft existing, find their entrance through it. 
The fact that the hyomandibular cleft of the Selachians being 
homologous with the tympanic cavity and the canals in the higher 
vertebrates, and exercising a similar function, is certainly very remark- 
able. This demonstration effects the removal of one difficulty, and 
that is the belief that the tympanic cavity and the canals first originated 
among the air-breathing vertebrates. In fact it was scarcely at all 
understood how for this purpose, a gill cleft, whose very existence de- 
pends upon its being constantly in water, could continue to exercise its 
true function, and still to some extent be subservient to the organ of 
hearing. This difficulty is completely set aside by the discovery that 
the sound-conducting function of the anterior gill cleft is not anew 
acquisition in land vertebrates, but that it also existed in their ancestors 
living in the water; and with these the reason [ursachliche momentj 
for this is also furnished, why this gill cleft could still survive, retain- 
ing its integrity to the very last and in the most advanced vertebrates 
in the scale of development, while the other gill clefts, originally pro- 
vided with respiratoiial functions, have disappeared without leaving a 
trace, having commenced in the Dipnoi and Amphibia with the devel- 
opment of a new respiratory organ. 
After what we have just demonstrated, the fact that the Urodela and 
several of the Anura possess no tympanic cavities or Eustachian tubes, 
is to be differently construed from what it has been heretofore. Here, REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
30 
without doubt, a retrogressive process is presented us, as in the snakes; 
and the alternative proposition, that in these forms a middle ear has 
not yet developed, is untenable. In fact it would be incomprehensible, 
if the closed foremost gill cleft of the higher Amphibia were to reopen 
itself and re-enlist its functions in connection with the auditory ap- 
paratus. Equally unintelligible would be the occurrence of the col- 
umella in Urodela—a part of the skeleton whose origin is closely asso- 
ciated with the development of the middle ear, and if it existed by 
itself its need could not be understood, inasmuch as no function for it 
could be discovered. 
The question now remains whether the apparatuses we have just de- 
scribed for the bony fishes and the Selachians originated entirely inde- 
pendently of each other, as appeared at the first glance, or whether 
there are not organs somewhere in existence which constitute the con- 
necting links between them, and allow a genetic connection of these 
apparently entirely different formations to be entertained. 
A direct comparison of the apparatuses in the Selachians with the 
Teleosteans leads to an unsafe result, inasmuch as the topographical 
appearances on the skulls of these forms are entirely different, and as 
a natural consequence the various relations of the parts cannot be com- 
pared with each other in detail; therefore it only remains for us to look 
about us for the intermediate forms and through them attempt the 
solution of the question. Such an absolutely intermediate form—of 
course only for the purpose mentioned—is Polypterus. While the cra- 
nium of this Sauroid, and particularly its maxillary apparatus and gill 
apparatus, very closely approach the Teleostean type, the Polypterus 
during life possesses a well-developed hyomandibnlar cleft, and in this 
respect reminds us of the Selachians. The inner, capacious opening of 
this cleft lies in the gill cavity; it is bounded mesia-lly by the epi- 
branchim of the first gill arch, posteriorly by the anterior margin of the 
hyomandibnlar, and laterally by the bones of the palatal arch. This 
wide hyomandibnlar cleft, takes an upward direction, lying close to the 
labyrinth region of the skull, to make its exit at the upper and lateral 
margin of the cranium in a slit-like opening, that is covered by two 
small dermal bones, which act like valves. In Polypterus the conduction 
of the sound-waves to the labyrinth can scarcely take place through 
the outer opening, closed as it is by the small dermal bones just referred 
to, so we must believe that the sound-waves enter at the inner and least 
difficult opening, as this does not open into the buccal cavity—as in 
the Selachians—but into the gill cavity, which is in complete communi- 
cation with the outer medium. 
A comparison of the hyomandibnlar cleft in Polypterus with the blind 
apical recess lying close to the labyrinth region in bony fishes places it 
beyond all doubt that they are homologous structures, and that this 
recess of the gill cavity, which was alluded to when speaking of the 
Teleosteans, is nothing more than the liyoinandibular cleft which has THE OSTEOLOGY OF AMIA CALVA. 
become widened and closed up at its dorsal aspect. An anatomical 
reason for this closure, I believe, must be looked for in the development 
of the hyomandibular in bony fishes. While in the Selachians this part 
of the skeleton is a slender cartilaginous rod; in osseous fishes it be- 
comes more extensive, in conformity with the greater development and 
differentiation of the muscular system of the maxillary apparatus, so as 
to form a broad plate. Correlated with this, we also find the articular 
facet for this bone in Teleosteans, extending so far as the postorbital 
process, which extension anteriorily closes the hyomandibular cleft. 
The relations of the main trunk of the facial nerve—the truncus hyoides 
mandibularis—affords the strongest proof that this extension was in 
anterior direction, or towards the anterior extremity of the body. In 
Selachians this nerve passes close to the hyomandibular, coursingdowu- 
wards in front of its anterior margin, while in the Teleosteans, in the 
majority of forms, it perforates the hyomandibular bone in order to reach 
the outer side. It requires no special demonstration to show that such 
an apparent perforation of the bone could only have been accomplished 
by its growth forwards, inclosing the nerve as it did so. At the same 
time the hyomandibular cleft had to be necessarily closed up and trans- 
formed into a blind recess in the gill cavity and with the same topo- 
graphical relations with the labyrinth as we have described for it. 
At the base of the orbital region, in the interior of the skull, there is 
a depression which is well defined both anteriorly and posteriorly, that 
reminds us to some degree of the sella turcica of the higher vertebrates 
(Plate II, Fig. 4). Posteriorly, this depression is continued beneath 
the processes of the petrosal bone, already referred to, where it termi- 
nates; anteriorly it is bounded by a bar of cartilage, which contains an 
osseous center at each lateral angle. At the base of this pit there is a 
breach in the primoidal cranium, already mentioned, which is closed in 
below by the parasphenoid. Iii the direction of the cavum cranii, speak- 
ing in a more limited sense, this pit is entirely closed by a strong mem- 
brane, which glistens like a tendon. This latter spans the space be- 
tween the anterior sharp margin of the united and horizontal wings 
of the ossa jpetrosa to the foremost cartilaginous bar. This membrane 
extends far up the lateral walls of the skull, and becomes attached 
about half way up to a sharp bony crest that is developed downwards 
and mesially from the ali- and orbito sphenoid (Fig. 7, The poste- 
rior part of this upper extension of fascia ensheaths the trigeminal and 
facial nerves near their points of exit Irom the skull; the anterior part 
of this fascia is the membrane that closes the optic foramen. 
This fascia divides off another space, situated below and somewhat 
laterally from the true cavity of the skull, which of course is intended 
for the brain. The greater part of this space is filled in with the well- 
known lymphoid fat tissue, found so extensively throughout the fishes, 
that is also contained in the remaining part of the cavum cranii in 
41 Dr. Sagemehl has failed to place these letters on his figure.—Tuans. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
Amia; there are also nerves and muscles to be found in it. The facial, 
with its ramus palatinus, and the trigeminus course through the postero- 
lateral divisions of this space, as already stated, between the mem- 
brane and the bony lateral wall of the skull for some distance before 
they arrive at their foramina of exit. In the anterior part of this space 
the membrane is perforated by the opticus. 
In the lower part of this cavity, which is separated as we have de- 
scribed from the brain case, are to be found the points of origin of the 
external rectus muscle. These arise near each other not far from the 
median line, close behind the cartilaginous transverse bar, already re- 
ferred to above, that forms the anterior boundary of the sella turcica; 
anteriorly these muscles diverge from each other, each to enter an orbit 
through the optic foramen on either side. So we find in Amia, as in so 
many of the bony fishes, a subcranial canal, which to be sure is but 
feebly defined, lacking as it does a superior osseous partition to divide 
it from the cranial cavity. The nervus abducens perforates the fascia 
from above, and immediately passes into the substance of the external 
rectus muscle, so that it is not visible in the orbit proper. In addition 
to this, the principal branches of the carotid artery are to be found iu 
this subcranial canal. Upon the membrane above this canal lie the 
hypophysis cerebri and the lobus vasculosns in a feebly developed funnel- 
shaped depression. 
We will now turn our attention again to the two ossifications, found 
in the lateral angles of the anterior cartilaginous bar. These cannot be 
observed from the outside, and it is only in the dissected skull and after 
the fascia has been removed, that they are exposed to view. Bridge 
has called these parial ossifications the basisphenoidea and declares that 
they are homologous with the well-known Y-shaped basisplienoid of 
many of the osseous fishes. 
This statement I fully indorse. If we bear in mind that besides the 
recti externi, the other muscles of the eye also make their appearance in 
the cavuin cranii, then the cartilaginous partition lying between these 
two groups of muscles must necessarily be implicated, and the two cen- 
ters of ossification already spoken of must through extension eventually 
meet and merge into each other, forming a non parial bone, situated 
between the muscles of the light and left bulbils. It is then that we 
have the conditions presented to us seen in so many of the bony fishes. 
If this explanation be not accepted, then we must see in Amia certain 
ossifications that occur in no other fish, and must deny Amia a bone of 
very frequent occurrence. 
The next thing before us is to compare the subcranial canal, which 
lodges the muscles of the eye in Amia with that canal as found in osse- 
ous fishes, and endeavor to ascertain whether it cannot be traced to a 
known and similar structure iu forms occupying a lower position in the 
scale. I will first briefly compare it with the canal as found in the 
Teleostei. THE OSTEOLOGY OF AMIA CALVA 
The principal difference between the subcranial canal for tlie eye 
muscles in Amia and that in bony fishes, is seen in the fact that in the 
latter it is separated from the brain case proper by an osseous partition, 
while in Amia this is composed only of membrane. In articles I have 
yet to publish, it is in}" intention to show how this osseous partition is 
developed in bony fishes from the neighboring bones, more particularly 
the petrosal, by their throwing out horizontal processes that meet to 
ossify in the median line of the skull. Commonly, too, this subcranial 
canal extends farther back in osseous fishes than it does in Amia, even 
to extend into the basioccipital. This results from the muscles of the 
eye being longer in these forms, and consequently a canal of proper 
length developes to accommodate them. 
Concerning the phylogenetic origin of the subcranial canal, Gegen- 
baur conjectures that the canalis transversus of the Selachians is the sub- 
cranial canal of the Teleostei, in which the muscles of the eye find lodg- 
ment.42 In the Selachians this canal passes from one orbit to the other, 
obliquely through the cartilaginous basis cranii, causing the two peri- 
orbital lymph sinuses to merge into one; in some cases it is separated 
from the brain case by membrane only. Immediately in front of this 
canalis transversus are found the openings for the carotids, which in 
some forms are separated from the former also only by membrane. In 
the orbits the recti muscles are inserted nearest to the anterior entrance 
of the subcranial canal. Quite close to this we also find—at least in 
several Selachians (Hexanchus)—the foramen of exit for the nervus ab- 
ducens. 
A great deal in the structure of the parts in question, so far as ex- 
amined in. Amia, goes to support this view. Above all, the fact must 
be noted that in Amia the canal separated from the cavum cranii is not 
entirely devoted to the eye muscles, as in the Teleostei, but is largely 
filled in by the lymphoid tissue. 
Now, since we have not the least ground for assuming that Amia is 
descended from forms in which the muscles of the eye were far better 
developed, and filled the space alluded to entirely, there is but one hy- 
pothesis possible, that Amia has in this region a preformed lymphatic 
fossa situated at the basis cranii, into which the points of origin of the 
recti externi only moved secondarily. But this preformed lymphatic 
space—if we are to judge from homologous structure in inferiorly or- 
ganized fishes—can only correspond to the canalis transversus of the 
Selachii, which, in Amia, is remarkably widened and spread out, and 
which has finally included the carotid canals and the surrounding nerves 
found near the exits of these vessels. At the same time its cartilaginous 
42 C. Gegenbaur, Untcrsiichungen zur vergl. Anatomie d. Wirbelthiere. Heft III. Das 
Koffslcelet d. Selachier, 1872, pag. 78. [C. Gegenbaur, Observations upon the Compara- 
tive Anatomy of Vertebrates. Part III. The skeleton of the head in Selachii, 1872, 
P* 78. J REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
roof was replaced by a membranous one. So long as such organizations 
exist and no intermediate forms are known to us between the primitive 
structures seen in the Selachians and the relatively and already widely 
differentiated organization of Amia, this view of Gegenbaur’s must remain 
an hypothesis; an hypothesis, to be sure, that lias much to support it. By 
accepting it, the survival of the transverse canal of the Selachii is ac- 
counted for in higher vertebrates, if nothing else, and one is not compelled 
to advance the dubious proposition that there exists in Amia, and in Tele- 
osteans descended from Amia, a canal beneath the cavum cranii, unique 
in the sense of being without antecedents, and whose importance and 
homology would be quite enigmatical. The olfactory region presents 
for examination two spacious canals in the interior of the skull, run- 
ning side by side, parallel and in an antero posterior direction, which 
are separated from each other by a broad cartilaginous septum, and 
which end in the foramina olfactoria at the base of the nasal fossae. 
In the canals, which are to be considered as the direct continuation of 
the cavum cranii, are to be found the very thick and firm olfactory 
nerves. They are composed of a strong neurilemma which surrounds 
a fasciculus of nerve fibers, some seven or eight in number, but loosely 
connected together, and among which, to all appearances, no anasto- 
moses take place. 
In fishes, as we are aware, two types can be distinguished, depend- 
ing upon the relations existing between the nerve center of the olfac- 
tory organs and their terminal filaments. In one case the bulbi olfac- 
torii of the olfactory mucous membrane lie close by, and are connected 
with the fore brain by a long tractus; a single olfactory nerve does not 
exist in this case, but rather, on the other hand, quite a number of short 
nerve fibers pass from the bulbus to the olfactory mucous membrane. 
In the other case the bulbi olfactorii are connected with the hemispheres 
of the cerebrum and arise as long and true olfactory nerves. At first 
sight it would appear as though the difference was not an essential one, 
and as t hough the bulbus olfactorius was no integral part of the brain, 
but simply a collection of ganglionic cells occurring in the course of the 
fibers of the olfactory, and could occupy divers positions. That it is, 
however, is clear when we see the typical, very characteristic, difference 
between the stout olfactory nerve, provided with a firm neurilemma, 
and distributed to the periphery from the bulbus, and the thin tractus, 
enveloped only in the delicate pia mater holding a central position with 
respect to the bulbus. This same fact was particularly dwelt upon by 
Stannius,43 that these two specified conditions as regards the position 
of the bulbi olfactorii are always independently present, that there is 
either a bulbus adjacent to the brain or one annexed to the olfactory 
membrane; cases in which a centrally located bulbus occurs in connec- 
43 Stannius, Das peripherische nervensystem d. Fisclie, 1849, page 2. [Stannius, The 
Peripheral Nervous system of Fishes, 1849, p. 2.] THE'OSTEOLOGY OF AMIA CALYA. 
tion with ganglionic enlargements at the distal extremity of the olfac. 
troy nervelets do not exist. 
Besides, there are—though very rare—intermediate forms known be- 
tween the two types we have indicated among fishes; cases, for instance, 
where the bulbus is placed half-way between the brain and the olfactory 
membrane, and where it is connected with the former by a thin, soft 
tractus; with the latter by a strong, firm nerve at least four times as 
thick. The only other case of this kind known up to the present time 
has been noticed by Stannius in the Gcidus raniceps fuscus; and I 
find quite a similar condition in the Characinidse, as in Hydrocyon and 
Alextcs. 
A mere superficial examination of these two types does not furnish 
us with sufficient data to judge from, and decide which is the primary 
form and which is the derived one. As in so many other cases, the ques- 
tion can ouly be decided by the systematic—based upon other con- 
ditions of organization—position of the forms that belong to one 
or the other type. We now find that the first type occurs in all Se- 
lachians, in Holocephals, and certain of the Teleosteau groups, long 
known to us as the primitive forms, as in the Siluroils, the Cyprinoids, 
the Gadidse, and, as I have found, also in the Mormyridae. 
The second type is extensively found in the Ganoids and in the great 
majority of the Teleosteans. With all this before us, no doubt can re- 
main that the first type is the primitive one, and that from it the other 
type has developed by a gradual shortening of the tractus and a length- 
ening out of the nerve. 
It appears that in the Teleosteans the development of the olfactory 
nerve is always brought about in the same way and with a uniform result. 
The enlargement of the orbits leads to a fenestration of the lateral or- 
bital wall at its anterior angle near where the bulbus olfactorius was 
originally located, as one can see very well in the Gharacinides ; this 
develojjment extending further gives rise to an olfactory nerve, which 
must of necessity pass through the orbits. These conditions appear to 
be quite constant among the Teleosteans. Among a great number of 
ver}7 diverse forms I have always found either an olfactory nerve in the 
orbit or a long tractus extending directly from the brain case to the nasal 
pit. 
In Hydrocyon, already referred to, the bulb us lies in a special eleva- 
tion in the orbito-sphenoid ; from it a nerve is given off that passes to 
the olfactory membrane, being free in the orbital cavity ; and a long 
tractus lying within the cavum cranii to the fore-brain, so that in this 
ease there is no exception to the general rule. 
. A remarkable exception to this rule is found in all the Ganoids. In 
these fishes a true olfactory nerve passes within the direct continuation 
of the brain case, and consequently proves to be a condition that must 
have arisen under circumstances to us nearly unknown and entirely REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
different from those of the bony fishes, and, therefore, bears no genetic 
relation to the latter. 
Lepidoateus alone seems to form an exception to this unvarying rule 
among the other Ganoids. The olfactory nerve in Lepidoxteus at first 
passes into a tunnel shaped osseous tube, formed by the alisphenoid. 
At the posterior part of the orbit it quits this tube and passes close 
beside the semicartilaginous, semimembranous interorbital septum; 
consequently at this point its course is free in the orbit. At the ante- 
rior part of the orbit both nerves enter a very long cartilaginous double 
tube, which corresponds to that portion of the long rostrum of this 
fish belonging to the primoidal cranium. At first glance we seem to 
have presented us here a method of development corresponding in 
every sense with that seen in the majority of bony fishes, yet this is 
by no means the case. As already stated, the fenestration of the lat- 
eral wall of the skull in the nasal region of bony fishes begins at the 
anterior part of the orbit, at the place where the bulbus olfactorius 
occupies a near position to the olfactory mucous membrane, and which 
leads to a marked separation of the same from the membrana olfactoria, 
and to the lengthening of the olfactory nerve. In Lepidostens this long 
double tube, in which the nerves are contained, is to be considered as 
the original direct continuation of the skull cavity; therefore the devel- 
opment of an interorbital septum in this fish cannot have come about 
in the same way that it did in the bony fishes, nor can the necessity for 
the origin of the olfactory nerve be looked for in this fenestration. This 
nerve must have originally in Lepidosteus, as well as in the other Ganoids, 
been contained for its entire length in a continuation of the brain case, 
which was separated by a median dividing partition into two canals; 
subsequently the lateral partition in the posterior interorbital part of 
this septum disappeared, and in this way the olfactory nerve came to 
lie in the orbit. 
In the course of this essay it would have been quite an easy matter 
for me, in more instances than one, to have pointed out the facts going 
to show that quite a number of the various structures in the bony 
fishes can be traced with tolerable certainty to Amia, and from this the 
opinion naturally arises that the same will apply to all the organs, 
and that Amia is in reality a direct ancestor of the family of Teleosteans. 
For this reason I have the more eagerly seized upon the opportunity 
to point out the conditions referred to above with respect to the devel- 
opment of the olfactory nerve, in which particular Amia has decidedly 
reached a higher degree of organization than certain osseous fishes 
lower down in the scale. 
In this place I will not omit the consideration of the morphological 
conditions of the peripheral olfactory organs of the Ganoids and Tele- 
ostei somewhat more critically, and compare them with corresponding 
conditions in the Selachians. THE OSTEOLOGY OF AMIA CALVA. 
In the lowly organized Sharks, as, for example, the Notidanides and 
Acanthias, there exists upon the inferior aspect of the snout, on cither 
side, a single nasal aperture, which is incompletely divided by two 
processes, the nasal flaps, which spring from its margin, and give rise 
in this way to a medial and a lateral entrance. 
In the more highly organized Selachians, in the Scylliaus, among the 
sharks, and in many rays, a more or less deep groove is found to extend 
from the medial entrance to the upper margin of the buccal aperture. 
This is the well-known naso-labial groove, which also appears in the 
ontogeny of the higher vertebrates, and for the closure of which the 
median nasal aperture is furnished with a valve, found on the mar- 
gin of the upper lip and opening in the direction of the nasal cavity. 
This latter corresponds to the inner nasal opening of the Dipnoi, Am- 
phibia, and Amniota. These structures have long since been de- 
scribed by Gegenbaur, and the question only concerns us with respect 
to the Teleosteans and Ganoids.44 According to previous notions—still 
accepted by Gegenbaur—the two openings of the nasal pit in bony 
fishes and Ganoids correspond to the imperfectly separated nasal valves 
of the lowly organized Selaeliii. Balfour45 has placed a different inter- 
pretation upon this. According to his views in the matter, the pos- 
terior nasal aperture of the higher fishes are homologous with the inner 
nasal apertures of air-breathing vertebrates, which by a gradual turn- 
ing of the axis of the nasal capsule have shifted their position from the 
upper lip to the superior aspect of the head. 
My observations upon fishes compels me to oppose this view, and 
adhere to the old opinion. There are two arguments that I must cite 
which conflict with Balfour’s notion : one of comparative anatomy and 
one of the history of development. In a number of Teleostei, among 
others, all native Cyprinoids examined by me, I found in the immediate 
neighborhood of the nasal apertures and in the dermal bridge separat- 
ing the anterior and posterior aperture, a small cartilage, that remained 
undescribed up to the present time, and that is strictly homologous 
with the nasal alar cartilage of the Selachians. This cartilage usually 
has the form of a figure 8, the two loops surrounding the nasal open- 
ings and the middle piece lying in the dermal bridge between the aper- 
tures. It is very intimately connected with the skin, so that it becomes 
a difficult matter to make a dissection simply trusting to the scalpel and 
forceps, but by the aid of a microscope, and carrying the incisions 
through the nasal region, one can very easily satisfy himself of its pres- 
ence. It possesses the characteristics of hyaline cartilage and differs 
44 C. Gegenbaur, Grundziige der vgl. Anatomie, II Aufl., 1870, pag. 754, und das Kopf- 
slcelet der Selachier, 1872, pag. 97 u 216. [C. Gegenbaur, Elements of Comp. Anatomy, 
II Edit., 1870, page 754, and tbe skeleton of tbe Selachian head, 1872, pages 97 and 
216.] 
45F. M. Balfour, Manual of Comparative Embryology, 1881, Yol. II, page 477. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
38 
from the cartilage of the primoidal cranium, with which it is in no way 
connected, by its much denser cartilage cells. 
In many cases among the Selachii, too, does the nasal alar cartilage 
encircle these apertures as a ring, sending out processes into the nasal 
valves. If one pictures to himself that the nasal valves of the Sela- 
chians have become merged with each other during their growth or de- 
velopment, and the cartilaginous processes contained within them be- 
come blended, there will result as a consequence a condition that can 
in no way be distinguished from the state of things as seen in the Tele- 
ostei. That this view is the correct one is shown by the history of 
the development of the nasal organ in the bony fishes. 
In newly-born fishes there exists on either side a simple undivided 
nasal aperture, as I have observed in the Lota vulgaris, in the Pike, in 
the Trout, and in the Chondostroma nasus. It is not until these forms 
have passed the embryonic stage does there occur, sooner or later, 
a division of this aperture into anterior and posterior nares. Both 
the median and lateral periphery develops a small patch of skin, 
directed towards the center of the aperture. Very soon these processes 
that correspond to the nasal valves in the Selachii become contiguous, 
the lateral process being behind the median in all of the specimens ex- 
amined by me. At this stage the nares in osseous fishes have reached 
the precise condition that remains permanently in Notidanides and 
Acantliias. 
In a short time these two nasal valves of bony fishes blend together 
and the narial opening receives its definite shape, at least for those 
forms in which the two apertures are situated close to each other. In- 
asmuch as the primary conditions are not exactly so arranged in Lota 
vulgaris, whose anterior and posterior nares, after it has arrived at 
maturity, are far removed from each other, there must occur in this 
species a widening of the nasal bridge and a separation of the nasal 
apertures at a later period (unfortunately I lack the material to illus- 
trate these stages). At any rate fishes with the anterior and posterior 
nares close together are to be considered as primitive forms, and from 
such, forms can be traced in which these apertures are far apart. Such 
forms, then, are to be considered as the highest in the scale of develop- 
ment in a certain direction, in which the narial apertures are far apart 
and are situated on the upper lip. 
Such formations among bony fishes occur in Ophisurus and kindred 
forms,46 in the family of Mursenoids, and, in fact, they have at the first 
glance a certain resemblance to corresponding structures in Dipnoi and 
perennibranchiates, and it does not appear improbable to me that this 
peculiarity of the Ophisurus led Balfour to assert a homology of the 
4,iLiitken, Nogle Bemaerkninger orn Naeseboreunes Stilling hos de i Gruppe med Ophisu. 
rus staaende Slaegter af Aale familien. Videmkabl. Meddelelser fra d. nuturhistoriske 
Forming i Ejdbenhavn, 1851. 39 
THE OSTEOLOGY OF AMIA CALVA. 
posterior nasal aperture in osseous fishes with the posterior nares of 
the air-breathing vertebrates. 
A comparison extended to a greater number of forms and the history 
of development clears up the actual state of affairs in this case also, 
and demonstrates that it is but an interesting case of “converging de- 
velopment” [“ I'onvergenten entwicJclung ”]. The position held by those 
Teleosteans which permanently possess but one nasal aperture on either 
side, as for example Belone, the Pomacentrides, many Ohromides, &e., is 
only to be determined with absolute certainty when we have a knowl- 
edge of the history of their development. If one, however, considers 
that the nearest kin to these fishes (Cyprinodonta, Labroidae) exhibit the 
ordinary conditions, it will hardly be out of place to simply assume 
that the dividing dermal bridge between the nasal apertures in the form 
referred to has been secondarily reduced. 
As in so many other structures, so in those of the nasal apertures, 
the lowly organized Selachii prove to be the starting point from which 
two diverging series can be traced; upon one side the higher fishes, on 
the other the air-breathing vertebrates. 
As I have already mentioned, the anterior and posterior nares in 
Amia are far apart, and, consequently, Amia represents a form that 
must, as compared with the ordinary bony fishes, be accepted as pos- 
sessing a higher state of development. The nasal bone is imbedded in 
the broad dermal bridge between the two nostrils. Under these cir- 
cumstances it is not at all strange that, in spite of the careful search I 
made for it in this fish, I could not find the trace of a nasal alar carti- 
lage in the vicinity of the nostrils. The nasal has taken upon itself the 
original function of the same, that is, to support the entrance to the 
nares, and thus rendered a nasal alar cartilage superfluous. 
To conclude the present article it only remains for me to draw a com- 
parison between the cranium of Amia and that of the Selachii, with 
which it may best be compared, and to particularize their resemblances 
and their differences. Taken as a whole the latter are fewer in number 
than one would at first suppose. The fundamental difference between 
the skull of Amia and that of the Selachians rests upon the appearance 
of the large connecting ossifications in the former. These ossifications 
either simply overlie the primoidal cranium, or they are connected very 
intimately with it, and without changing their form, replace structures 
in it that were originally cartilaginous. 
The first appearance of the larger uniting masses of osseous tissue 
among fishes denotes one of the greatest and most far-reaching steps in 
the progress of the process of development of vertebrate animals. It 
indicates the first appearance of a tissue that, as a protective and sup- 
porting material, proves far more suitable than cartilage. A glance at 
a series of skulls of Selachians and Teleosteans will be sufficient at once 
to demonstrate the great significance of this “occurrence.” REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
40 
The entire organization has become changed. A pleasing, graceful 
structure has taken the place of the clumsy Selachian skull. The deli- 
cate and rounded contours of the latter are replaced by angular, and 
quite often by oddly-shaped skulls, on which the grooves for muscular 
attachment and tendon insertion are distinctly marked. The new ma- 
terial substituted for the building up of these structures far surpasses 
the old, not only in its capacity for resistance, but also is greatly supe- 
rior to it in its fitness for plastic modelling. In this particular, one finds 
very marked gradations even among the higher fishes. In their rounded 
contours, and in the imperfect ly developed muscular grooves and crests, 
the bony Ganoids and a number of the Physostoma remind one very 
much of the Selachians; and it is only in those groups of fishes exhibit- 
ing the highest development, more particularly Acanthopterygii, that 
the types of extreme differentiation come into bold relief. 
Leaving out of consideration the fact that it partly consists of differ- 
ent material, the primoidal cranium shows but few points of difference 
from that of the Selachii. In the first place, by the co-ossification of 
several vertebrae, the occipital region in Amia has attained a distinct 
morphological value, differentiating it from the corresponding regions 
in the Selachians, without having its form essentially changed by the 
process. Compared with the Selachians it has increased considerably, 
but in length only, which is sufficiently accounted for by the circum- 
stance just mentioned. 
The posterior part of the skull cover, in the vicinity of the occipital 
region, presents a structure that already esssentially exists in the Se- 
lachii. The median, cartilaginous process, pointing posterially, is 
present in the Notidanides, being developed there as a cartilaginous 
crest. Nor is it difficult to recognize in the medial projections occupied 
by the exoccipitals in Amia, the cartilaginous elevations developed upon 
the projecting posterior arches of the Selachians. The posterior lateral 
angles of the skull, formed in Amia by the intercalare, are also very 
well developed already in some of the sharks, as, for example, in Scyl- 
lium. Between the crest of the posterior arch and the last-mentioned 
lateral projection of the skull in the Scyllia there can already be recog- 
nized a depression in the cranical vault, extending into the region of 
the postorbital process, which in Amia is bridged over by the overlying 
dermal bones, closing in the temporal fossa}. In the region of the laby- 
rinth of the Selachians we find this cavity closed up on the side towards 
the cavum cranii; in Amia it is widely opened, probably a fenestration 
proceeding from the periphery of the acusticus foramen. 
Upon the outer aspect of the labyrinth region, the changes occasioned 
by the presence of the articular facet for the hyomandibular, are the 
most striking. I have already availed myself of the opportunity to 
point out, in the higher fishes, the extension of the hyomandibular for- 
wards as far as the postorbital process. THE OSTEOLOGY OF AMIA CALVA. 
At this point I would remark, that in the matter of position of the 
hyomandibular articulation, it is the Notidanides among all the Sela- 
chians, that still most resembles Amia and the Teleostei. 
The parietal grooves which occur in the skull cover of many Sela- 
chians, and which include the broad, blind terminal parts of the aquae- 
ducti vestibuli, are missing in all the Ganoids and Teleosteaus. This 
has evidently something to do with the very imperfect development of 
the aquaeducti in the higher fishes as compared with that structure in 
the Seiachii. 
At the base of the primoidal skull we invariably find in higher fishes 
a fenestration in the region of the hypophysis cerebri that is lacking 
in the Seiachii. 
Postorbital and antorbital processes occur in most of the Seiachii as 
well as in Amia and most all the Teleostei. 
The optic foramen of the Seiachii—already exhibiting evidences of 
increasing size—is represented in the orbital region of Amia by an ex- 
tensive vacuity. 
The cartilaginous peduncle which supports the eye in many Selach- 
ians, is in Amia reduced to a fibrous cord. Only the merest traces exist 
in the orbits of Amia of that basal projecting ledge of the primoidal 
cranium and the vault as they occur in the Seiachii. 
The very characteristic vacuity which occurs in the prefrontal cover- 
bone of the primoidal skull in the Seiachii is wanting in Amia, but ap- 
pears to be present in certain families of osseous fishes, in Oypriuoids 
and Characinids. 
Not a few differences in the structure of the nasal region between the 
Seiachii and the higher fishes, including Amia, can be made out. 
While the nasal apertures in the Selachians are situated upon the lower 
aspect of the snout, in higher fishes they are without exception on the 
lateral or upper plain of the head; besides, the well-developed nasal 
capsules of the Seiachii are reduced to quite flat pits in Amia and in 
the bony fishes. 
A structure homologous with the nasal alar cartilage of the Sela- 
chians is entirely wanting in Amia, but can be pointed out, as demon- 
strated above, in certain bony fishes. 
Still another, not unimportant, difference in the structure of the nasal 
region in the higher fishes and that of the Selachians is to be recognized 
in the fact, that in the former articular facettes for articulation with the 
anterior end of the palatine arch are developed on the inferior aspect 
of the region referred to. 
The characteristic interrupted rostra, occurring in many Selachians, 
are wanting in the higher fishes, either entirely or are replaced by sim- 
ple uninterrupted structures, that approach in this respect the rostra 
of the Notidanides. 
The recapitulation of our investigations go to prove that there are 
several structures in the organization of Amia that cannot be regarded REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
as liaviog been derived through progressive development from existing 
structures in the Selachii. 
To these belong the diverse courses of the ramus palatinus in the 
Selachians and in the higher fishes, the relations of which cannot be 
directly derived from one another. Yet it is not improbable that in 
this case we are dealing with a substitution of very different and appre- 
ciable nerve branches, as often happens in fishes. 
In most of the plans of structure in the skull of Amia a direct progress 
in development can he discerned in parts from those that already exist in 
Selachii ; and it is particularly the Notidanides—the least differentiated 
of the Selachians—which present the most evident relations to Amia for 
recognition. 
It would be very difficult to specify the distinguishing characters be- 
tween the cranium of Amia and that of the Teleostei. There are but very 
few characteristics to be found in the skull of Amia that could not be 
found in one or the other of the families of the Teleostei, and these 
few distinguishing characters are not restricted to Amia, but are also 
found in other Ganoids. In this category belongs the continuate, non- 
fenestrated, cartilaginous cover of the primoidal skull, in which, among 
the Teleostei, vacuities are always discoverable, but it has preserved 
its integrity in the Accipenserides among the Ganoids. A second im- 
portant distinction is the absence of the supraoccipital in Amia and all 
the other Ganoids, while in the Teleostei it occurs quite constantly. 
The third distinction—already described above—refers to the course of 
the olfactory nerve in a direct prolongation of the brain case—is shared 
by Amia with all the other Ganoids. 
Postscript.—Just as this article had passed into the hands of the 
printer, I received a copy of the treatise by J. Van Wijhe, “ Upon the 
visceral skeleton and the nerves of the Ganoids” (Netherlands Arch, 
f. Zoolog., Yol. Y., Part III, 1882), in which the cranial nerves of 
Amia are described. I am glad that Van Wijhe agrees with me in all 
the essential points. I must also state that Van Wijhe has invited 
attention to the importance of the mucus canals in determining the 
bones that overlay the skull (/. c., page 228).47 
47 Dr. Sagemliel’s paper is completed by a resume of the lettering of the figures, or 
an “ Explanation of figures in the plate,” but I have omitted this, as the figures are 
separately described in their appropriate places here.—Trans. THE OSTEOLOGY OF AMIA CALVA. 
PART II. 
Henricus Franque, doctor of medicine and surgery, published his 
famous monograph, entitled Amiae Calvae, Anatomian Descripsit Taba- 
laque Illustravit, in Berlin in 1847. The pamphlet form of this unique 
paper, familiar to all anatomists who have worked upon or are interested 
in the osteology of fishes, now lies before me. It extends through seven 
pages, written in Latin, upon the skeleton of Amia calva, with refer- 
ences to some of the soft parts; description of figures in the plate, and 
the plate itself. This latter presents eleven figures, four of which are 
devoted to the skeleton; Fig. 9 to a scale; while the remainder illus- 
trate various things in the soft anatomy. Fig. 1 is an upper view of 
the skull, with all the “ cover-bones ” retained in their normal positions. 
In Fig. 2 we are presented with a left lateral view of the entire skele- 
ton of a moderately sized fish of this species. Fig. 3 gives an infe- 
rior view of a part of the cranium, with the entire hyobranchial appa- 
ratus removed. 
These figures are all well done, and in a style peculiar to themselves, 
bold and clear, though lacking in some points of minute detail. Three 
of these figures have been copied for me by Mr. H. L. Todd, and re- 
duced by photograph for the purpose of adding to this article the figure 
of the lateral view of the entire skeleton. This will be valuable in 
showing the general relation and arrangement of the bones. 
The excellent article of Bridge48 is good as far as it goes, but he treats 
of the skull of Amia only, and we still have to resort to other works to 
study the extremely interesting points in the remainder of the skeleton. 
Moreover, as Mr. Bridge’s paper was published in the Journal of Anat- 
omy, it is not particularly available to a very large number of Ameri- 
can workers. Indeed, this valuable periodical is not subscribed for by 
nearly as many of our libraries and institutions as it should be, nor as 
it deserves to be. To present a good account of the entire history of 
the skeleton of Amia is the principal object I had in view upon under- 
taking the present paper. Just previous to Dr. Sagemehl’s paper, 
which constitutes Part I of this memoir, Bridge very truly tells us, in 
his article, wThen reviewing all that anatomists had done with the skel- 
eton of this Ganoid up to 1877, that “ the cranial osteology of living 
Ganoids has been hitherto but partially investigated; and even those 
genera that have been described by the older anatomical writers will 
abundantly repay renewed investigation now that the researches of 
Parker, Gegenbaur, and Iluxley have thrown so much light upon the 
morphology of the vertebrate skull.” 
48 Bridge, T. W.—The Cranial Osteology of Amia Calva. Jour, of Anat., normal and 
pathol. Yol. XI, Pt. IY, page 603. Edinburgh and Lond., July, 1877. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
“ Agassiz,49 it is true, has given to us an elaborate account of Lepi- 
dostens, and the earlier description of Polypterus by H. Muller50 has 
been supplemented by Dr. Traquair’s51 opportune paper; while to Dr. 
GUnther and Prof. Huxley52 we are indebted for exhaustive accounts of 
the skeleton of Ceratodus.” 
“On the other hand, lam not aware that, beyond the more or less brief 
accounts to be found iu John H. Muller’s Vergleichende Anatomie der 
Myxinoiden53 we have any detailed descriptions of Spatularia, Acipeuser, 
or Amia; and the anatomical student who may wish to acquire any com- 
plete knowledge of these genera must content himself with the above- 
mentioned references, or with such facts as he may be able to glean from 
such anatomical text-books as Huxley’s Manual of Vertebrata, Owen’s 
Comparative Anatomy, or the Crundziige der Vergleichenden Anatomie of 
Gegenbaur. More especially is this true of Amia. The zoological char- 
acters of this genus have been described by several Zoologists. Vogt54 
first detected its true position among the Ganoids and removed it from 
the Clupeoid Teleostei, with which it had been placed by Muller;55 and 
Hyrtl56 and Franque57 have described the generative organs and visceral 
anatomy. But I am not aware that there exists any connected account 
of the osteology of the skull of this genus, or that the skull has been 
figured.” 
Jordan and Gilbert place the Amias in the order Halecomorplii, and 
the single species known, the subject of this paper, Amia calm, in 
the only family in the order, Amiidse. These authors give as the geo- 
graphical range of this fish the great lakes and sluggish waters from 
Minnesota to Virginia, Florida, aud Texas. In describing the external 
appearance of Amia calva, they state that it is of a “ dark olive or 
blackish above, paler below; sides with traces of dark reticulate mark- 
ings ; lower jaw and gular plate often with round blackish spots; fins 
mostly dark, somewhat mottled. Male with a round black spot at base 
of caudal above, this surrounded by an orange or yellowish shade. In 
the female this spot is wanting.”58 
On the 12th of February, 1883, I took in a seine near New Orleans, 
La., four specimens of Amia. Two of these were alike; they were very 
dark above, the ocellation at the base of the tail, large, very black, and 
the emargination a brilliant buff color. But what was still more strik- 
49 Agassiz, Poiss, Foss, Tom. 11. 
50Abhandl, A. K., Wiss. ; Berlin, 1844. 
51 Journal of Anatomy, Yol. IV. 
82 Phil. Trans. 1871; 5 Proe. Zool. Soc. 1876. 
63 Yergl. Anat. d. Myx., Berlin, 1835. 
MAnnales des Sciences Naturelles, Tom. xxiv, Heart and alimentary canal figured. 
56Muller’s paper, “ Sur les Ganoides et sur las classification naturelle des Poissonst,y 
is translated by Vogt in the xxv. vol. Ann. Sci. Nat. 
56 A. K. Wiss. Wien., 1855. 
87 Amice calvoa Anatomia, Berlin, 1847. 
88 Jordan & Gilbert. Syn. Fishes of North Amer. Bull. U. S. Nat. Mus., No. 16, 
1882. THE OSTEOLOGY OF AMrA CALVA. 
ing, and what differs from Jordan and Gilbert’s description, the pecto- 
ral and ventral fins in these two specimens were of a bright Prussian 
green. The two remaining specimens were smaller fish, much lighter 
in color, being sort of a clay-brown, with the fins of a similar shade, 
and less mottled than the others, with the caudal ocellation present, 
only not so large or brilliant. 
OF THE GANOID PLATES. 
This series of investing bones of the cranium have been so thoroughly 
described by Sagemehl above, and by Bridge in the Journal of Anat- 
omy, that I shall content myself with a running review of them, with 
special references to the fine specimen before me, from which I made 
my drawing. (Plate IV, Fig. 16.) 
The most extraordinary thing about Bridge’s description is that he 
seems to have secured a specimen for his dissection, wherein the parie- 
tal dermo-plates were in one piece, without any trace of a suture be- 
tween them. To the united bone this anatomist gave the name of the 
dermo-supraoccipital, which is commented upon by Dr. Sagemehl in 
Part I of this paper. 
It seems hardly possible that Bridge could have been mistaken in this 
matter, as he made special search for the sutural trace dividing them, 
aware as he was of Owen’s already having mentioned that two plates 
occupied the site of his dermo-supraoccipital. Moreover, the sculptur- 
ing would be different on a single plate, as the rugosities would radiate 
from a single center to the borders as they do in the other plates. 
In all the specimens that I have examined, including the one before 
me, these parietal plates, existed as described by Dr. Sagemehl, even to 
the detail of the suture not terminating in tliQ median line posteriorly 
as shown in Plate I, Fig. 1, Pa. This was the condition found and de- 
scribed also by Franque, who gives a very good representation of a 
superior view of the dermal plates in this fish. (Plate II, Fig. 7.) 
The arrangement in my specimen is precisely the same as in the speci- 
men drawn by this latter anatomist, the right-hand plate extending 
more anteriorly and the suture between the bones deflected to this side 
posteriorly. Figure 7 should show, however, more marked serrations 
of the margins of the bones anteriorly, as .they are invariably found to 
be so in nature. 
External to the parietal plates on either side we find a longer and nar- 
rower bone, sculptured as the rest, which is the squamosal. (Plate IV, 
Fig. 16, Sq.) 
Behind the squamosals and parietals, the hinder margins of which 
form nearly a straight suture across the skull, we find the supra- 
temporals, two rather long, triangular plates placed transversely with 
their blunted apices meeting in the median line (Fig. 16, S. tp.). These 
two plates shut out from superior view the two forked limbs of the 
posttemporals upon which they rest. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
Of all these plates on the superior aspect of the skull the frontals are 
by far the largest. Posteriorly they articulate with the squamosals 
and parietals as already described, while on either side they make room 
for the postorbitals. (Plate IY, Fig. 1G, Fr.) 
Their anterior bodies are separated from the hinder margins of the 
nasals by a considerable interspace. This is bridged over by a delicate 
membrane, which is continuous with a similar tissue that extends across 
the gap between the frontal and lacrymal on either side (Plate IV, 
Fig. 16, jn.). In prepared skulls where this structure is allowed to 
remain and dry it becomes very thin, and by cutting through it we ex- 
pose the posterior narial apertures and the primoidal cranium beneath.. 
The nasals are oval bones that articulate with each other in the 
median line by means of a markedly dentate suture. Wedged in between 
them anteriorly we find the azygos and subtriangular ethmoid (Plate 
IY, Fig. 1G, Fa. and Eth.). Upon the outer side of each nasal, in my 
specimen, there lies a smaller plate, of a spindle-like form, that corre- 
sponds to the plate described by Bridge as the preorbital, although its 
posterior end occupies a point only about half-way distant between the 
teeth and the anterior margin of the orbit (Fig. 16, An.). This author 
also figures a small ossification below this preorbital, which does not 
occur in my specimen. Dr. Sagemehl seems to have found a like 
structure, but attached no significance to it. 
Bridge describes the ethmoid very concisely when he says, “ The 
dermo-etlimoid (Eth.) is somewhat T-shaped, with its anterior trans- 
verse part slightly concave from side to side. It overlies the prenasal 
process and the premaxilke. Each end of the transverse part is in 
contact with the preorbital bone, while the stem of the T passes back- 
wards between the nasals, separatiug them for about a third of their 
extent.”59 
The periphery of the orbit is subelliptical in outline, and six of the 
dermo plates contribute to its boundary. The upper half of the cir- 
cumference is formed by the free margin of the frontal, as the vault of 
the orbital cavity is made by this bone. Its lower half is bounded by 
the five remaining plates, of which the superior postorbital is the largest, 
and the rear suborbital the smallest, though the latter contributes the 
greatest share to the peripheral circumference. 
The most anterior bone of this suborbital chain, I call, in common 
with other anatomists, the lacrymal, as it is quite constant in the class, 
both in the position it usually occupies and its occurrence. The two 
smaller plates, immediately beneath the orbit, are true suborbitals, and 
their number and arrangement vary greatly throughout all fishes. 
Behind the large triangular postorbitals, we find a group of small 
bone-plates, forming a vertical chain, that fills in the space between 
these bones and preoperculum (Plate IV, Fig. 1G 1c, k', 1c"). These small 
plates seem to vary in their size, form, and number, for on the opposite 
69 Jour, of Anatomy, July 1877, page 608. THE OSTEOLOGY OF AMIA CALVA. 
side of my specimen I find but one of them, which is situated just be- 
low the squamosal and shaped like the one marked k" on the right side. 
All four of the opercular bones are presentand thoroughly developed. 
(Fig. 16, Op., S. op., I. op., and Pr. op.) 
The preoperculum is a long, narrow, crescent-shaped bone, that touches 
the squamosal above and contributes to the articulation for the mandi- 
ble below. Only a narrow strip of its external surface, just within the 
posterior border, along its entire length, shows the sculpturing common 
to the other bones. Beyond this its surface is smooth, and its anterior 
border makes a very intimate union with the hyomandibular and sym- 
plectic. 
The three remaining opercular bones are beautifully sculptured all 
over their external surface, and remind one not a little of those rugose 
surfaces as seen in some of the handsome marine shells. Of these bones 
the operculum is by far the largest; it articulates with an elongate facet, 
placed upon the upper and posterior angle of the hyomandibular. In 
common with the remaining two of the group, its anterior border is over- 
lapped by the preoperculum. The upper and lower margins of the sub- 
operculum are closely applied throughout their entire extent to the op- 
posed margins of the operculum and interoperculum. This element is of 
a more irregular form than either of the others, its upper border being 
deeply concave to admit the rounded lower anterior angle of the oper- 
culum, while the inferior one is quite straight. Against this last, the 
base of the interoperculum is applied, this latter plate having somewhat 
the form of an isosceles triangle, with its rounded apex directed below. 
The inner surfaces of these three last opercular bones are smooth and 
unmarked by any sculpturing, as their opposite sides are. A rounded 
ridge crosses the suboperculum obliquely, extending from its upper pos- 
terior angle to the lower anterior one. Anteriorly, the extremity of the 
maxillary (Fig. 16, Mx.) is bent towards the median line, and articu- 
lates in a socket immediately behind the outer end of the premaxillary, 
being covered over above by the preorbital and lacrymal plates. Its 
entire lower margin is armed with a single row of thickly set teeth. 
These decrease in size from before, backwards, and, like the larger ones 
on the premaxillary are very sharp and gently curved inwards. The 
hinder half of the upper border of the maxillary supports an additional 
thin plate of bone, as seen in so many of the Teleostei. This is the ad- 
maxillary, and its form is very much the same as in bony fishes (Fig. 
16, a). Both the maxillary and adinaxillary are sculptured on their 
outer surfaces after the fashion of the other ganoid plates described 
above. 
Bridge says: u In comparing the skull of Amia with the skulls of 
certain of the Silnroidei, and notably with that of Clarias, it is inter- 
esting to notice that, in addition to the more obvious and less impor- 
tant points of resemblance between the two genera necessitated by 
the flattened condition of the head and a foreshortening of the prefrontal REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
region, there is a close agreement between them in the number and re- 
lations of their ganoid plates.”60 
Of the Mandible.—A lateral figure of this very complex bone presents 
us with a partial view of four of the elements that enter into its com- 
position (Fig. 10). As usual, the chief part of the ramus is made up 
by the dentary (Fig. 16 and PI. V, 17, 1) or d). This bone expands 
behiud to articulate with the angular and surangular on lateral view, 
while internally this expanded part is broadly concave, which concav- 
ity is arched over by the splenial. Anteriorly, it meets the fellow of the 
•opposite side in a rather strong symphysis, the two bones developing 
a single row of powerful teeth. These are of a conical form, curved 
backwards, and very sharp at the apices. In Fig. 10 is shown where 
two of these teeth have been shed, and the shallow pits they leave be- 
hind them. The row of smaller teeth beyond, as shown in this figure, 
belong to the splenial or the plates connecting it with the symphysis. 
Upon lateral view we may also see the angular and surangular to the 
extent shown in Fig. 10, as well as the ossification marked £ to be de- 
scribed further on. 
The angular is the next in point of size to the dentary. Its outer 
surface is convex and sculptured in the same manner as the ganoid 
plates, while posteriorly it forms part of the articulation of the jaw. 
Above this element we find the surangular splint, which is carried up 
to form the coronoid process, to be tipped with cartilage at its apex. 
Bridge, after liis careful investigation of the mandible, says, in his pa- 
per quoted above, that it “is an unusually complex structure, as each 
ramus consists of not fewer than fourteen distinct elements. Mechel’s 
cartilage persists as a thin axial band of cartilage. Its distal end is os- 
sified, and forms a small cylindrical mento-meckelian ossicle (Plate V, 
Fig. 17 of this paper, mt. nik.), which lies in a groove on the inner side 
of the symphysial end of the dentary (d). The proximal end of the car- 
tilage is the seat of at least four distinct ossific centers. Of these, three 
are arranged in a linear series proceeding from the angular extremity of 
the mandible. These are referred to in the annexed plates ffigures] as 
a, b, and c. Of these the ossicles a and b form the anterior and poste- 
rior boundaries of the articular cup for the quadrate, and are separated 
from each other by that portion of Meckel?s cartilage which forms the 
bottom of the cup. The bone marked c is much smaller than the other 
two. That part of Meckel’s cartilage adjacent to the articular cup is 
produced vertically upwards and forwards into a well-marked ‘ coro- 
noid process’ (cr). The base of this process is the seat of an ossifica- 
tion (b) which forms the outer side of the articular cup, and fits into 
the cup-shaped distal end of the preoperculum. Thus these three bones, 
a, b, and c, contribute to the formation of the concave articular surface 
for the quadrate.” 
60 Ibid., page 609. THE OSTEOLOGY OF AMIA CALVA. 
u Hitherto it has been currently stated in anatomical text-books that 
the mento-meckeltan bone at the distal end, and the articular bone at 
the proximal end of Meckel’s cartilage, were the only elements of the 
mandible really formed by ossification of the cartilage itself, yet in 
Ainia there can, I think, be but little doubt that at least four, and 
probably five, ossific centers are developed in the axial cartilage. 
Whether one of the centers a, b, c, and d represents the os articulare 
of the Teleostean mandible, or whether the latter bone is really a com- 
pound bone resulting from the coalescence of the persistently distinct 
elements of Amia, is not very evident; but I am inclined to think that 
the os articulare is not so simple a bone as it has hitherto been supposed 
to be. As the Meckelian cartilage is the distal, or ventral half of the 
first postoral visceral arch, though it may not be possible to point out 
the special homologies of the mento-meekelian, and the ossicles a, &, c, 
and d, with the ossifications found in the ventral halves of the remain- 
ing postoral arches, yet I think that we may roughly correlate those 
ossicles with the interhyal, epiliyal, ceratohyal, and hypoliyal of the hy- 
oidean series.” 
“It may also be that the cartilaginous ‘coronoid process’ is another 
instance of the tendency manifested by the first postoral arch to develop 
forward connective outgrowths, of which the orbitar process and the 
palato-pterygoid arcade are conspicuous examples in the proximal half 
of this arch. In addition to the mandibular elements above referred to 
there are, in addition, several membrane bones. The ossification a has 
a small ganoid plate (d. «)61 attached to it, which appears at the extreme 
tip of angl& of the jaw.” 
I show in Plate Y, Fig. 18, the large triangular splenial in situ. 
This bone does not run out to the symphysis of the rami anteriorly, but 
is, iudireetly connected with it on either side through a chain of five 
very much smaller plate-like bones. These each support a tuft of good, 
strong teeth, and very much remind one of the dental plates arranged 
along on the superior aspect of the branchial arches. I am surprised 
that Bridge did not notice this when he compared the numerous ossifi- 
cations of Meckel’s cartilage with these arches, as the simile is equally 
striking. Teeth are found also over quite an extensive area on the 
upper part of the splenial, though here they are very fine indeed (Fig. 
18). When the splenial is in position, a large subcompressed conical 
space is inclosed between it and the outside bones. The \>ase of this 
cone is directed inwards and forms the opening to the sulcus in ques- 
tion. Both the symplectic and the preoperculum contribute to form the 
cup for articulation with the mandible, and the quadrate supplies an ar- 
ticular semi-globular head for the same purpose. As already described, 
the opposed surfaces on the jaw are developed from special ossific cen- 
ters. 
61Tkis is the ossicle marked z in Fig. 16 of this paper REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
A large azygos gularplate partially fills in the inter-ramal space (PI. 
YI, Fig. 20, G. pi.). This plate, occupying as it does the same position 
as the paired structures of similar description in Polyterus, is held to 
the surrounding bone by the skin and other soft parts. Its anterior 
end develops an expanded tip, which is connected by stronger liga- 
ment to the symphysis of the jaw. Externally, the surface is sculpt- 
ured like the ganoid plates on the roof of the skull, while its internal 
surface is quite smooth. The homology of this plate is still unsettled. 
It has been spoken of as replacing the urohyal. A very long, osseous 
gular plate is found in the inter-ramal space among the Elopidae. 
Of the Cranium.—So minutely has Dr. Sagemehl described this part 
of the skeleton of Amia calva, that I will here but hastily view the 
points for examination, and introduce them merely as a recapitulation 
to fill in my own account of the skull. 
To examine the cranium we must take the head of a fresh specimen, 
remove the shoulder-girdle, all the ganoid plates, and other structures 
below and laterally that do not belong to it. Then, from a superior 
view, we have presented us for examination a large, central quadrilat- 
eral, cartilaginous track (Fig. 6). At the anterior extremity of this, we 
seethe intermaxillary (Sm.); the premaxillary (Pmx.), and the prefrontal 
(Prf). Occupying a lateral and at the same time a mid position we see 
the postfrontal (Fig. 6 Psf), while it is bounded behind by the opisthotic 
at the outermost angle (Fig. 6 Jc, intercalate, Sagemehl, op. o, opisthotic 
of Bridge), just within which, and above it, we find the exoccipital 
(Ex)—this latter is marked ep. o. in Bridge’s figure, he considering it 
the epiotic. Behind these two bones we observe in Fig. 6 a segment 
marked 01, this is the occipitale laterale of Sagemehl, and the exoccipital 
of Bridge. To the rear of this again we find the occipital arches, so 
well described by the former author in Part I of this paper. 
Now, turning the cranium over, we have presented us upon its infe- 
rior aspect, for examination (Fig. 2), first, the pair of vomers (vo.), situ- 
ated anteriorly ; then traversing the basis cranii longitudinally the para- 
sphenoid Ps. (pa.s in Bridge’s figure). An almond-shaped area in the 
middle of this latter bone is covered by fine teeth, while the anterior 
thirds of the vomers support others which are very much larger and ar- 
ranged in a circular group. The vomers and parasphenoid must now 
be carefully removed; then we have before us the ossifications shown 
in Fig. 3—the base of the cranium. Proceeding from before back- 
wards, there are the premaxillary (Pmx.); the septo-maxillary (Smx.); 
the prefrontal (Prf.)’, the orbito-sphenoid (Os.)} the alisphenoid (As.); 
the postfrontal (Prf.); petrosal (Pe.) (the prootic of Bridge); the opis- 
thotic (Jc.)} and the occipitale laterale (01.) spoken of above. The infe- 
rior view of the co-ossified occipital vertebrae is also to be seen from 
this side. 
Upon a direct lateral view (Fig. 5) may be seen the premaxillary 
(Pmx.) ; the septo-maxillary (Smx.); the prefontal (Prf.) ; the orbito- THE OSTEOLOGY OF AMIA CALYA. 
sphenoid (os.)) the post-frontal (Psf.)) the alisphenoid (As.); the pro- 
otic (Pe.)) the epiotic (Ex.); the opisthotic (Jc.); the exoccipital (Ol.)y 
and the lateral view of the co-ossified “ occipital arches” of Sagemehl. 
Lastly, viewing the cranium directly from behind (PI. Ill, Fig. 13), we 
may see the opisthotic (Jc.); the exoccipital {01.)) the epiotic (Ex.)y 
and the rear view of the vertebrae that have co-ossified with the occiput. 
Should the vomers and parasphenoid be allowed to remain on, these 
may also be seen upon lateral views. 
As the preceding paragraphs give the differences in nomenclature 
as used by Sagemehl and Bridge, it will be unnecessary for me to re- 
mark upon it further in this connection. 1 will simply say here that 
from this point on, I propose to adopt the terms employed by the lat- 
ter author in designating the various bones. 
The vomers are cleft behind to admit the parasphenoid, while they 
are united for their anterior thirds by suture. 
Near its middle, the parasphenoid throws off on either side a lateral 
wing, which in each case passes upwards in a curve to bound the pro- 
otic anteriorly, lying between the foramina of exit for the fifth and 
seventh nerves, and finally terminates against the postfrontal. 
Viewed from below, the united premaxillce form a crescent-shaped bone, 
that supports a complete single row of sharp, incurved teeth. These are 
second in point of size of the various teeth found upon this part of the 
skull 5 the largest being on the palatines, and the smallest on the pos- 
terior margins of the maxillaries, that is if we do not take into consid- 
eration those minute teeth found on certain areas of the bones of the 
mouth. The ascending portion of the premaxillce is carried back be- 
tween the nasals and the sub-nasal cartilage as far as the frontals, 
being covered in this situation by the nasals and ethmoid. Each as- 
cending process is pierced near its center by an oval foramen for the 
passage of the olfactory nerve. 
We now come to examine the chondro-cranium proper and the ossifi- 
cations that take place in it. Removing the bones we have just 
described, the remaining part, pyramidal in form, has its broad end 
posteriorly, while it terminates in front in the prenasal process. The 
cartilaginous vault is unpierced by any foramina, and neither promi- 
nent otic or nasal projections exist, as seen in many of the Teleostei. 
Accommodating itself to the form of the cranium, the brain-box passes 
between the orbits to have its apical anterior end terminate between the 
prefrontals against the hinder margin of the lamina perpendicularis, 
which in turn terminates anteriorly in the prenasal process, referred to 
above. 
The supraoccipital is absent and the basioccipital is much elongated, 
owing to the fact that it has appropriated two of the leading vertebrae 
of the column, the neural arches of which ride it above. 
Exoccipitals are well developed, and contribute both to the peripheries 
of the foramen magnum and the opening for the vagus. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
Independent epiotic, opisthotic, sphenotic (postfrontal), and prootic 
osseous elements are represented in the auditory capsule, but the pro- 
otic is the only one that passes through the cranial wall to be discerned 
upon the inner aspect of the brain-case. The pterotics are absent. 
By the proper interchange of the nomenclature, minute descriptions 
of all these elements are contained in Part I. Bridge’s descriptions 
are also terse and clear. For those who may by chance in their reading 
wish to compare the investigations and studies of Bridge upon the 
cranium of Amia, in his article in the Journal of Anatomy, with Part I 
of this paper, the following table will be found to be useful in the con- 
nection, presenting as it does in a concise form a few of the differences 
interminology employed by these two authors; where the number of the 
figure is given in parentheses it is reproduced in this memoir. 
Table. 
Sliufeldt. 
Figures and let- 
tering. 
Bridge. 
Sagemehl. 
Fig. 1 + (Eth.) 
Fig. 1 -f (Na.) 
Fig. 3 -j- (Smx.) 
Fig. 2 -f- (Pmx.) 
Fig. 1 (An.) 
Fig. 3 + (Pr/.) 
Fig. 16 -f- (F. or 
Fr.) 
Fig. 3+ (Psf.) 
Fig. 1 + (Pa.) 
Fig. 1 -f (Sq.) 
Figs. 1,16 + (S. 
t. p. and Esc ) 
Fig. 1,16 + (Sc. 
or Pst. T.) 
Fig. 1 + (01) 
Fig. 5 -f (Ob.) 
Fig. 5 -f (Ex.) 
Fig. 5 4- (Pe.) 
Ethmoideum. (Eth.) 
Nasale. (Na.) 
Septomaxillare. (Smx.) 
Praemaxillare. (Pmx.) 
Antorbitale. (An.) 
Prsefrontale. (Prf.) 
Frontale. (F.) 
Postfrontale. (Psf.) 
Parietale. (Pa.) 
Squamosum. (Sq.) 
Extrascapula. (Exc.) 
Suprascapula. (Sc.) 
Occipitale laterale. (01.) 
Occipitale hasilare. (Ob.) 
Occipitale externum. (Ex.) 
Petrosum. (Pe.) 
Absent. 
Intercalare. (Jc.) 
Vomer. (Vo.) 
Parasphenoid. (Ps.) 
Orbitosphenoid. (Os.) 
Alisphenoid. (As.) 
Septomaxillary 
Premaxillary 
Preorbital 
Prefrontal 
Septomaxillary 
Premaxilla 
Preorhital 
Prefrontal 
Postfrontal 
Parietal 
Squamosal 
Supratemporal 
Posttemporal 
Exoccipital 
Basioccipital 
Epiotic (Ep. o) 
Prootic (Pr. o) 
Postfrontal (sphenotic) 
Derm o-supraoccipital 
Parietal 
Suxrratemporal 
Posttemporal 
Exoccipital 
Epiotic (Ep. o) 
Prootic 
Opisthotic (Op. 6) 
Fig. 3 4- («7c.) 
*Fig. 2 + (To.) 
Fig. 2-|- (Ps.) 
Fig. 2 -f (Os.) 
Fig. 2 + (As.) 
Opisthotic 
Parasplienoid 
Orbitosplienoid 
Alisphenoid 
Parasphenoid 
Orbitosphenoid 
Alisphenoid 
A means other figures than the one quoted in the second column show the same hone similarly 
lettered. 
The mucus canals have been so thoroughly treated in Part I that I 
will not revert to them again here. In the mandible the single ramal 
branch commences in the angular element to pass through the dentary 
for its entire length, to meet the fellow of the opposite side at the sym- 
physis. This branch connects with the system of the rest of the skull, 
where the angular articulates with the preoperculum, through which 
latter bone the lateral mucus canal passes, after having traversed the 
supratemporal and squamosal. 
Both the orbitosphenoids and alisphenoids are more or less circular 
bones. This is due to the fact that during their extension and develop- 
ment they have not proceeded sufficiently far as to impinge upon neigh- 
boring osseous elements for the major part of their peripheries. The 
position of these bones is well shown in Fig. 3, and others. 53 
THE OSTEOLOGY OF AMIA CALVA. 
The alisplienoid develops two processes and is pierced by two fora- 
mina. Of the processes, the smaller one arches over the canal for the 
orbital muscles; the other is the “ descending process of the alisphe- 
noid.” The larger foramen passes the first division of the fifth nerve; 
while the outer and smaller one transmits the second and third divis- 
ions. 
In each orbitosphenoid we see a deep cleft to allow for the exit of 
the optic nerve from the brain-case. They are supported by the coa- 
lesced trabeculae below, articulate with the alisphenoids laterally, and 
support the cover-bones above. 
The eye-muscle canal; the shallow pituitary fossa; the trabecular 
groove; the anterior clinoid process or wall, with the ossifications in its 
substance; the “ prootic bridge; ” the openings of the carotid arteries; 
and other structures in this region have all been sufficiently dwelt upon 
in Part I. 
The lamina perpendicularis being in cartilage, Amia in consequence 
lacks the true ethmoid found in Polypterus. In referring to the septo- 
maxillaries Mr. Bridge says that “The two ossifications above referred 
to as forming the antero-lateral angles of the internasal area are peculiar 
to Amia amongst Ganoids. They lie, one on each side of the prenasal 
process, and appear to be ossifications in the cartilage of the floors of 
the nasal capsules; inferiorly they rest upon the upper surfaces of the 
vomers. There can, I think, be but little doubt that these ossicles 
(sep. mx.) [Fig. 3 and others of this paper smx.] are homologous with 
the paired endosteal ossifications, which are to be found at the distal 
end of the great prenasal rostrum in the Pike. In fact, if the prenasal 
region in Amia were produced anteriorly into a rostrum comparable to 
that of the Pike, these bones would exactly resemble in position and 
relations their homologues in the latter fish.” 
“These ossicles would also appear to be homologous with the septo- 
maxillary bone described by Mr. Parker as existing in the flow of the 
nasal capsules in the Frog; and also with similar bones in the Ophidia. 
A section carried through these bones and adjacent cartilage in Amia 
would resemble in all essentials the various sections giveu in Mr. Parker’s 
paper (Phil. Trans,, 1871) on the development of the frog’s skull (PL X)” 
The next step in our dissection is to carefully remove the suborbital 
chain of bones 5 the maxillary and ad maxillary; and the ganoid plates 
overlying the nasal and premaxillary regions, then we have exposed in 
the prepared skull the elements of the 
PALATO-PTERYGOID ARCADE. 
This is made up of the palatine, entopterygoid, ectopterygoid, with 
which are associated the metapterygoid, hyomandibular, symplectic, and 
quadrate. While intimately related to it is the preoperculum, and less 
so the operculum itself, which latter merely articulates with the 
hyomandibular. The entire arrangement of these bones in Amia is REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
upon the Teleostean type, and all the elements found in the bony 
fishes are present. 
Mr. Bridge, in his figure (Jour. Anat., 1877, Fig. 6) representing what 
I here have drawn in my figure 19, has inserted cartilage among the 
palatine and the several pterygoid bones. This material I have failed 
to find in this situation in any specimen of the age represented in either 
figure that I have thus far examined. 
The palatine (PI. VI, Fig. 19, PI.) is thoroughly well developed and 
armed with two sets or kinds of teeth; the first of these, and the larg- 
est in this part of the skull, form a single row upon the lateral or exos- 
teal portion of the bone in continuation with those on the premaxillae. 
Others, very much smaller, are arranged internal to these on the en- 
dosteal lamina of the palatine and continue the vomerine series. An- 
teriorly at its apex the palatine is grooved to receive the inturned pro- 
cess of the maxillary, which is here wedged in between this bone and 
the premaxillary. The palatine is also in relation in this region with 
the septomaxillary, vomer, and prefrontal. It possesses the unique 
character among Ganoids in its relation with the latter bone in being- 
carried in front of its articulation, a condition well known to us among 
the bony fishes. 
The entopterygoid forms the major share of the floor of the orbit, ar- 
ticulating by overlapping sutures with the bones it comes in contact 
with, while its entire buccal surface seems to be overspread with very 
minute teeth. This latter condition applies also to the ectopterygoid 
(PI. VI, Fig. 19, Enpt. Ectp.), this bone being additionally armed with a 
row of fine teeth upon its lower border containing the palatine series. 
It connects the palatine and quadrate but is separated from the meta- 
pterygoid by a thin strip of the entopterygoid. 
The metapterygoid (Fig. 19, M. Pt.) is shaped like a fan with its han- 
dle, tipped on the end with cartilage, directed upwards toward the 
orbit. This is the ascending process of the metapterygoid. The fan 
part terminates in an angle at either extremity; the anterior angle 
nearly touches the alisphenoid, while the posterior one overlaps the 
hyomandibular. 
So close is the union between the quadrate and symplectic, that these 
two elements appear to form one bone. Taken together they are shaped 
somewhat like a spherical triangle, the lower angle of each being dis- 
tinct, the symplectic terminating above the quadrate, each to bear an 
articular facet for the mandible. In the case of the quadrate this is 
convex and hemispherical, while in the companion bone it is crescentic 
and concave, being in reality, one-third of the socket of which the preo- 
perculum affords the remaining two-thirds. 
It requires severe maceration in order to separate the symplectic from 
the quadrate, the union almost amounting to true anchylosis. 
The hyomandibular (Fig. 19, H. M.) is obliquely pierced by an ellip- 
tical foramen, near its centre for the exit of the facial nerve. Above, 55 
THE OSTEOLOGY OF AMIA CALVA. 
its straight border articulates in an elongated facet in the cartilage 
over the otic region. Behind, it supports a large circular facet, borne 
upon a subsessile stem, for the operculum (ro). 
Its relation with the cartilaginous interhyal and the symplectic 
agrees very closely with typical Teleosteans. 
Bridge seems to be inclined to believe that the angle formed anteri- 
orly by the long axes of hyomandibular and symplectic, which give these 
bones their directions, may account for the movement forward of the 
metapterygoid in this Ganoid. In most Teleosteans this latter bone is 
directly over the quadrate, and not in front of it. In this I cannot 
agree with him, but attribute the position of the metapterygoid in 
Amia, entirely to its unusual size, as compared with the neighboring 
bones, rendering it a physical impossibility to assume any other posi- 
tion. This bone in a bass (Micropterus salmoides) before me is squarely 
over the quadrate and rather behind it, whereas the anterior angle 
formed the hyomandibular and symplectic is quite as acute as it is 
in Amia, but the quadrate is relatively very much smaller. 
Of the hyoidean and branchial arches (Fig. 19).—In this connection 
I will also describe the extraordinary series of branchiostegal rays in 
Amia.62 There are twelve of these appendages, articulating through 
ligamentous attachment, well within the posterior borders of the epihyal 
and ceratohyal, upon their outer surfaces. They diminish gradually 
in size from above downward, slightly overlapping each other about 
half way down the series. The superior and largest has a somewhat dif- 
ferent form from the others, being a long ellipse, with a well-marked 
longitudinal groove close to its upper border on its external aspect. 
This surface likewise is sculptured all over quite as thoroughly as one 
of the ganoid plates and in a similar manner. It articulates both with 
the epihyal and ceratohyal. The sculpturing gradually disappears as we 
near the middle of the series, through it can be faintly discerned to the 
very anterior ray. In life, these rays lap each other anteriorly, the set 
from one side over the set from the.other, under the throat, where they 
constitute a striking feature and unique ornament. 
The articulation of the hyoid with the liyomandibular and sym- 
plectic, through the intervention of the cartilaginous interhyal with this 
bone and the epiliyal is very similar to the state of affairs as we find it 
.among ordinary teleostean fishes. Holding a mid-position in the arch, 
the ceratohyal is a strong, well developed bone, bent at an elbow 
near its middle (Fig. 19 c. hy). The arch is completed by the lumpy 
little hypohyal, borne at its anterior extremity (H. hy). No evidences 
exist of an ossified glosso-hyal. 
The basibranchial elements of the branchial apparatus are composed 
chiefly of cartilage with very little bone; one of the number seems to be 
62 Mr. Bridge seems to have unfortunately secured an imperfect specimen of the mud- 
fish in this particular, as he affirms that there are but eleven of these rays, that is 
hardly a good reason, however, for figuring but tew.—(Jour, of Anat., July, 1877, p. 
609, and Fig. 6, Plate IY.) REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
better ossified than the others. There are altogether four of them, and 
they are much compressed from side to side. The arches proper are 
five in number, the first four being complete, with the usual elements 
present. They are completely beset with groups of minute teeth, which 
ride them above, and come off like scales during maceration. The gill- 
rakers are very small and thick-set. 
Mr. Bridge completes his article in the Journal of Anatomy by a very 
valuable and concise summary. As this occupies but little more than a 
page, and contains so much, and in such a convenient form, of use in the 
present connection, I feel quite sure the reader will think me warranted 
in reproducing it here, and no doubt be thankful for it. 
This author says that “In summarizing the result of *the foregoing 
description of the skull of Amia, I would lay stress on the following 
facts, as having a special bearing on the affinities of Amia to the more 
highly specialized osseous fishes and to the amphibia. 
“I. The possession of a complete ehondrocranium, i. e. the absence of 
feuestrse in the cranial roof, as in Lepidastens and the Pike (Esox). 
“II. The existence of a nearly complete series of otic bones, compris- 
ing a large pro-otic, with internal plates forming a characteristic “pro- 
otic bridge’7 in the floor of the cranium, opisthotic, epiotic, and sphe- 
notic elements. 
“III. The presence of twh ossific centers, partly exosteal and in part 
endosteal, forming rudimentary basisphenoid. 
“IV. Septo-maxillary ossifications in the subnasal lamina, as in 
Clarias, Esox, Kana, and Ophidia. 
“V. The interorbital prolongation of the cranial cavity, separating 
distinct, paired ali- and orbitosphenoids. 
“VI. The prolongation of the palatine in front of its prefrontal artic- 
ulation, and the connection of its anterior end with the inwardly 
curved process of the maxilla. 
“VII. The possession of a T-shaped dermal ethmoid overlying the 
premaxillce, and the close analogy in number and relations between the 
investing ganoid plates of Amia and those of the Siluroidei, and espe- 
cially with those of Claries, as has been previously described. 
“VIII. A complete series of opercular bones, a preoperculum anchy- 
losed to the hyomandibular and sympleetic bones, an operculum, an 
interoperculum, and a suboperculum. 
“IX. The presence of a jugal bone [admaxillary (a)] attached as in 
Teleo'stei to the upper edge of the posterior part of the maxilla. 
“X. The existence of a mento-meckelian ossicle, as in Spatularia, and 
of several additional centers of ossification in the proximal extremity 
of Meckel’s cartilage. 
“XI. The presence of five accessory dentigerous splenial elements in 
addition to the normal mandibular splints, as in the young Polypterus 
and Ceratodus among Ganoids, and in Siren and larval Salamanders 
among Amphibia. THE OSTEOLOGY OF AMIA CALYA. 
11 In continuing in its cranial structure the anatomical facts expressed 
in paragraphs I-IX inclusive, Amia differs from all other living Gan- 
oidei, and exhibits distinct and decided affinities to such generalized 
types of physostomus Teleostei as the Siluroidei, Cyprinoidei, &c. On 
the other hand, in common with all other Ganoids, Amia possesses sev- 
eral points of resemblance with larval and adult forms of Amphibia, 
especially as regards the structure to which attention has been directed 
in paragraphs IV, X, and XI.” 
u Moreover, in the angulation of the mandibular arch, caused by the 
forward growth of its metapterygoid element, we have a repetition of 
an arrangement characteristic of the adult frog, and of certain Sela- 
chians, Xotidanus. But notwithstanding these evidences of widespread 
affinity it is evident that if, in addition to the above-mentioned facts, 
we credit Amia with the possession of cycloid scales, non-lobate fins, a 
nearly homocercal tail, and note the absence of spiracles, the Teleostean 
affinities predominate; and it may be asked whether, despite certain 
peculiarities in structure of its generative organs and bulbous arteriosus, 
the gap between the ganoid Amia and the physostomus Teleostei is not 
less than need be expressed by ordinal distinction. It may be that just 
as Polypterus and its near ally of the same family are the sole surviv- 
ing examples of the otherwise long extinct order of Crossopterygian 
Ganoids, so the Amiidse are the sole survivors of those widely-general- 
ized Ganoidei out of which more specialized Teleostei were directly 
evolved.” 
Xow, if it were my intention to carry the comparative studies of the 
skeleton of Amia further than Dr. Sagemehl has in Part I, I would enter 
the tempting fields offered by the minute examinations that could be 
made of other American Ganoids and compare them in every particular 
with our subject. Then comparisons made with the complete skeletons 
of Elops and Megalops would be particularly interesting, and on some 
future occasions these may be treated as I have endeavored to treat 
Amia in this paper. But to undertake such comparisons here would 
lead me far beyond the intention and scope of my original plan. 
It does, however, fall within the limits of this plan to present here a 
concise review of the skull and other parts of the skeleton of a well- 
specialized Teleostean, more particularly the skull. Such a review, it 
is hoped, with its illustrations and figures, will be valuable, from a com- 
parative point of view, taken in the present connection, as well as form- 
ing a groundwork for future studies or the observations of others enter- 
ing upon the study of the anatomy of fishes for the first time. 
Of a Teleostean slcull.—For my review of this part of the skeleton of 
a Teleost and for references to such other parts of the osseous system as 
I propose to enter upon, I have chosen a specimen of Mieropterus sal- 
moides. This was done because the large-mouthed black bass is a'fish 
of pretty general distribution in the United States, and consequently REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
58 
will be more easily available for those who wish to compare my state- 
ments with the specimen of the fish before them. 
In the adult Micropterus we find the entire skull very thoroughly 
ossified, with the vast majority of the bony elements pertaining to this 
part of the Telesotean skeleton present. Viewing the cranium from 
above, we have presented us for examination, on its hinder calf, five 
prominent crests; two on either side and a median one. This latter 
appears to be developed entirely by the supraoccipital (Plate XI, Fig. 
27, S. 0). If the free margins of the lateral crests were produced ante- 
riorly they would all meet at a point just beyond the supraethmoid. 
The inner pair of these crests are developed by the parietals (Fig. 27, 
Pa.), and they terminate posteriorly in horizontally flattened processes 
formed by the epiotics (Fp. 0). On the outer side the crests are formed 
by the squamosals, which in their turn are completed behind by the 
pterotics, which here are vertically compressed plates (Fig. 27, Sq. Pt. 0). 
The crest part of the squamosal is formed of two lamina, between which 
passes the squamosal mucus canal. A deep sulcus is found between 
the hinder ends of the parietal and squamosal crests, at the base of 
which we find a large triangular foramen, covered over in the recent 
state by membrane, just beyond the squamosal, ou either side the 
crescent-shaped and upper part of the postfrontal (Pt. /). The mid- 
region of this aspect of the cranium, and constituting the vault of the 
orbits, is formed by the broad frontals (Fr.) with a tolerably distinct 
suture still visible between them. Here an interesting condition of the 
mucus canals presents itself. This consists in a large V-shaped cov- 
ered canal with its convex arc just beyond the crest of the supraoccip- 
ital, where it has in the median line a common opening. The limbs 
of this covered V pass through each frontal, to open on the surface, in 
elliptical apertures, a little behind the prefrontals. They then tunnel 
again to open once more directly forward on either side of the supra- 
ethmoid and over the surface of the nasals. From our superior aspect 
we also have a good view of the upper surface of the sculptured pre- 
frontals (Fig. 27, Prf), forming the anterior walls of the orbits. Beyond 
this the region is occupied by the supraethmoid and upper part of the 
vomer. It is pierced on either side of the promontory formed by the 
supraethmoid, by the nasal foramen, and the opening for the olfactory 
nerve. 
Upon a lateral view of the cranium we are to note the deep articular 
facet for the hyomandibular extending from the postfrontal along be- 
low the squamosal crest, and occupying the lateral portion of this bone. 
Here we see, also, that the postfrontals dip pretty well down on the 
lateral wall, wedging in between the alisphenoid and prootic (Fig. 27, 
As. Pr. O. and Ptf.). The opisthotics occupy their most usual site in 
front of the exoccipital on either side. Beyond the alisphenoid I find 
an ossification I take to be the orbitosphenoid, it is in contact with the 
alisphenoid behind, runs down the lateral wall of the cranial cavity, 
while it forms a prominent ridge traversing forwards on the under side THE OSTEOLOGY OF AM IA CALVA. 
of the frontal. Above each one we observe a canal for the passage of 
the olfactory nerve from the brain-case to the nasal capsule. The exit 
for the trigeminal nerve is bridged across by a thin lamina of bone, 
apparently afforded by the prootic. Another and smaller osseous bridge 
is found immediately to the rear of this iirst one. Upon this view the 
suture between the ex- and basioccipital is plainly visible, while a deep 
concavity exists in the region through which it is directed. 
The parasplienoid (Fig. 27, Pr. $.), prefrontal, and vomer may also be 
studied from a lateral view, and the basisphenoid is likewise brought 
into sight. (B. 8.) 
A rear view of the cranium presents most conspicuously among its 
points for examination the circular and conically concave facet for ar- 
ticulation with the centrum of the atlas. It is developed by the basi- 
occipital and somewhat lower in position than the horizontal plane 
of the parasphenoid. Above it are two elliptical facets, directed down- 
wards, backwards, and inwards, for articulation with similar surfaces 
on the first verterbra. Between these exoccipital facets and yet well 
above them is the foramen magnum, a heart-shaped opening looking 
downward and backward. The suture dividing the exoccipitals is 
plainly visible in the median plane of its inferior circumference. 
Just above the exoccipital facet, on either side, we find the vagus 
foramen for the exit of that nerve. Anterior, and at the same time in- 
ternal to these openings, is to be found a shallow facet, one on each 
side. These are for the heads of a pair of occipital ribs that articulate 
at these points, and which I have elsewhere described.63 
The exoccipitals meet just above the foramen magnum, at which point 
they receive between them the thin lamelliform crest of the supraocci- 
63 Shufeldt, R. W. “ Osteol- 
ogy of the large-mouthed Black 
Bass.” Science, No. 65. Cam- 
bridge, May 2, 1884, p. 532. 
These ribs are of so much iu- 
terest and at the same time so 
much importance from a mor- 
phological point of view, that 
I feel warranted in reproducing 
my original figure of them in 
Left lateral view of cranium of Micropterus salmoides, showing , 
...... „ „ .. . b this foot-note,illustrating what 
occipital ribs, Oc. r. Half size of tlie original specimen; from ’ . * 
author's drawing published in Science (No. 65.) S. eth, supraeth- have said abo\ e m the text, 
moid: vg. vagus foramen; and the other lettering the same as As already announced in Sci- 
figures in this paper. encCy I have since detected them 
in the Tunny (0. Thynnus) and suspect their occurrence in some of the Scombridie. 
It will be interesting for those now engaged in dissecting fishes, or others investigat- 
ing the anatomy of the class, to be on the lookout for these structures. The family 
Centrarchidse should receive particular attention in this regard, and of these the 
genus Lepomis stands among the first to be suspected. Their exact location and con- 
stancy should be noted. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
60 
pital. The body of this latter bone makes up the major portion of the 
quadrate surface, upon this aspect of the cranium, contained between the 
spur-like epiotics and the facets of the exoccipitals. Beyond this sur- 
face the pterotics project on either side, in about the same horizontal 
plane with the superior circumference of the foramen magnum. 
An inferior view of the cranium presents principally for our inspec- 
tion the two bones, parasphenoid and vomer (Fig. 27, Pr. 8. vomer not in 
sight). These, as we well know, are in the adult bass, azygos bones 
lying in the median plane. The parasphenoid, by the assistance of the 
basioccipital, forms a large oval-shaped surface beneath the canal for 
the eye muscles; it then contracts again, at which contraction it throws 
up on either side a plate-like process that has been nearly entirely ab- 
sorbed by the prootic. The bone beyond this shows another dilation, 
but not as large as the rear one. It then contracts to form the solid bar 
that lies between and beneath the orbits (Fig. 27, Pr. 8.), which anteri. 
orly runs above the vomer and under the prefrontals. 
The vomer of Micropterus is a very prominent bone. It is carried 
back well on the under surface of the parasphenoid in a pointed proc- 
ess, the suture between the two bones being easily distinguishable, 
although this part of the vomer in other respects appears like an ex- 
tension of the parasphenoid. Anteriorly it forms a beak which is 
rounded in front, carried well below the general surface beneath, the 
inferior aspect of this latter part being semicircular in outline and 
thickly studded with fine teeth. 
Of a few of the general points to be noticed about the cranium of 
Micropterus, we have the raised pedicle on the line extending from the 
prefrontal to the vomer. This pedicle supports an articular facet, di- 
rected downwards and forwards, for articulation with a rounded and ele- 
vated facet on the anterior end of the maxillary. The bone I have called 
supraethmoid in Fig. 27 is so termed by Parker in his Salmon’s skull, 
because it overlies the cartilaginous ethmoid in that fish; the element 
is, however, generally termed the ethmoid, or the medium ethmoid 
(Gegenbaur), and I feel myself at liberty to apply either name to it. 
The ethmoid is a very proper one. In this bass the prootics form the 
anterolateral walls of the eye-muscle canal, but do not meet below in 
the median line, as they do in some of the Teleostei. Between them in 
the median line, and springing from the'floor of the brain-case, we find 
a delicate arch of bone, with its convexity directed forwards, that 
comes down to meet the parasphenoid. This arch belongs to the 
basisphenoid (Fig. 27, B. 8.) and is found in many of the bony fishes. 
As the relations of many of these bones, described above, on the 
inner cranial wall, show very well in a vertical, longitudinal sectiou of 
the cranium of our common American perch (Perea americana), I figure 
such a section here in preference to Micropterus, where the bound- 
ing lines or sutures among the elements are not so evident or easily 
studied. THE OSTEOLOGY OF AMIA CALTVA. 
Some of these cranial bones may be considered to form certain groups, 
of which four enter into the occipital region. These are the basioccipital, 
the two exoccipitals, and the supraoccipital. In Mieropterus, as in all 
fishes, the basioccipital is the direct continuation of the spinal column, 
and possesses many of the characters pertaining to the vertebrae. The 
exoccipitals inclose the aperture of the foramen magnum entirely in 
this fish, only partly in many others. The supraoccipital, or the upper 
segment, supports a median crest that corresponds to the neural spine 
of the vertebra. Its form varies exceedingly, as well as its size. 
Another group of bones inclose the ear capsule, and have had names 
bestowed upon them that denote the relative position they bear to it. 
First and most constant among these is the prootic ; it is either pierced 
by or limits the foramen for the trigeminal nerve. Second in order 
come the epiotic, which overlies the superior vertical semicircular canal. 
It, in the vast majority of fishes, always forms a projecting process. 
Next we have the opisthotic, a segment lying in front and to the side of 
the exoccipital, but does not appear on the internal aspect of the brain- 
case nor bear any direct relation with the labyrinth. To these three 
bones Mr. Parker added a fourth, the pterotic, which in fishes forms the 
postero external angle of the cranium. In most bony fishes it articu- 
lates with the outer limit of the posttemporal. I may add here, in pass- 
ing, that these bones form the “ periotic mass,” and are the same found 
in the petro-mastoid portion of the temporal in man and the other 
higher vertebrates. It is unnecessary to say more than 1 already have 
above about the squamosal and postfrontal. The latter is sometimes 
termed the sphenotic, and assists often the former in the formation of 
the articular facet for the liyomandibular. This is the case in Microp- 
terus. 
Beyond these, in another group, we have the alisphenoid at the sides 
and behind and the orbitosphenoids anterior to them, while the basi- 
sphenoid is found below. This latter bone, we have already shown in 
the black bass, forms an osseous partition between the two sets of or- 
bital muscles; it may be absent in some of the Teleostei and very small 
in others. 
On the cranial vault the parietals are not always separated from each 
other by the intervention of the supraoccipital as they are in Mieropterus, 
nor are the frontals always separate bones, they sometimes forming only 
a single piece, as in Gadus. The segments of the ethmoidal region have 
been sufficiently described above. They all, the prefroutals, ethmoid, 
and vomer, vary greatly in size, form, and relationship throughout the 
class. 
To still further illustrate the relatious that may exist among the bones 
in crania of osseous fishes, as well as some of the remarkable forms they 
may assume, I am indebted to Professor Gill for the loan from his private 
cabinet of the cranium and portion of the palato-quadrate arch of a speci- 
men of Albula rulpes and an imperfect cranium of Megalops, the latter REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
62 
being the only one he had in his possession. I chose these two crania, 
from which I made the drawings that illustrate this essay, because we 
find in the organization of both Albula and Megalops at least one feature 
that they possess in common with Amia. In Albula it is the peculiar 
structure of the bulbus arteriosus and in Megalops the presence of the 
gular plate. But in describing the crania of these two forms I will con- 
fine myself strictly to the two specimens in question, and only describe 
what is to be seen in them. The sequel will prove that there is much of 
interest and importance. Judging from the cranium alone, the complete 
dissection of Albula will well repay the anatomist some day, for this part 
of its skeleton presents many points of the greatest interest and diver- 
sity in development. 
There is but this one species of Albula known to science, and its prin- 
cipal habitat are the warm tropical seas, where it is abundant. With 
us, however, it has been taken from Cape Cod clear around to Southern 
California (Jordan and Gilbert.) This fish, we are told by the authors 
just quoted, possesses “no gular plate.” 
Viewing the cranium of Albula from above, and proceeding with our 
examination from before, backwards, the first object that strikes us is 
the extraordinary ethmoid it possesses. (Plate XII, Fig. 30, Fth.) 
This bone is fashioned off in front so as to remind one very much of 
the snout of a pig. From this part it extends backwards in a median 
crest, deeply grooved above. This runs in between two prolongations 
developed by the frontals, and can be seen opposite the letters Xa2 in 
Fig. 29. Anteriorly the ethmoid projects over the parasphenoid, which 
bone abuts against it. From the base of its median crest it sends 
downwards and outwards on either side a plate-like portion, the mar- 
gins of which curl up for their posterior moiety. A vacuity of an ellip- 
tical outline exists in the crest auteriorly as it reaches the snout-like 
protuberence, and only the grooved part is carried over to meet this por- 
tion of the bone. This foramen can only be seen upon a lateral view as 
shown in this figure. 
The frontals (Plate XIII, Fig. 30, Fr.) are very extensive bones and 
cover nearly the entire superior aspect of the cranium. Their union 
with the ethmoid is of such a nature as at first to give one the impres- 
sion that the two are but one bone, and indeed the suture between them 
is not always discovered at once. Just above the prefrontals, bones 
which they overshadow all to their outstanding wings, they present on 
either side of the extension of the ethmoidal crest the openings of 
two very large mucus canals. These open behind in slit-like foramina, 
just beyond the letters Fr. (Fig. 30), as well as in more minute open- 
ings behind and to the outer side of them. The frontals completely 
overarch the orbits, lap down upon the postfrontals and squamosals, 
while posteriorly in this specimen the left-hand bone appears to overlie 
the fellow of the opposite side as well as both the parietals. These 
latter bones are comparatively small plates of a quadrilateral outline, THE OSTEOLOGY OF AMI A CALVA. 
with the supraoccipital wedged in between them from behind. The 
squamosals present quite an extensive surface on superior aspect, and 
they too have running through them longitudinally, with anterior and 
posterior apertures, capacious mucus canals. These apertures can be 
well seen in Fig. 30, the hinder elliptical one just below the letters 8q.t 
and the anterior one opening out over the surface of the prefrontal. 
(Ptf.) 
A certain amount of sculpturing is seen upon the surface of the 
frontals, parietals, and squamosals, in the form of a decided radiation 
from a central point. This is most perfectly marked in the frontals, 
where fine radiating lines are carried clear to the peripheries of these 
bones. A longitudinal depression is found between these latter seg- 
ments in Albula, of a triangular form, being narrow and deep anteriorly, 
shallow and broad behind. The epiotic and supraoccipital we will re- 
serve for description until we come to deal with the posterior aspect of 
the cranium of this fish. Fig. 30 shows very well indeed the extent to 
which these bones may be seen from a superior view of this part of the 
skull. 
The inferior view (Plate XIII, Fig. 31) of the cranium of Albula is even 
more interesting than the superior, owing to the numerous points pre- 
sented for our examination. This view shows us how far the ethmoid 
overhangs the parasphenoid, for the narrow, little transverse suture 
between these two bones is distinctly visible. Just beyond it, on the 
former bone, we observe a globular protuberance, deeply cleft by a 
transverse facet, which I take to be the articulation for the upper jaw. 
Behind this ethmo-parasphenoidal suture the vomer is seen. This bone 
is shaped like a little fan, the handle being directed backwards in the 
median line, while the expanded portion lies in the horizontal plane 
with a rounded margin anteriorly. Within this we find a double row of 
sockets in the specimen evidently intended for a series of minute teeth. 
Posterior to the vomerine region the parasphenoid presents a considera- 
ble excavation mesially, while opposite this the bone develops, on either 
side, a horizontal wing-like lamina. Each wing is raised above the gen- 
eral inferior surface of the parasphenoid, being between that bone and 
the prefrontal behind, while anteriorly it merges into it again. Outside 
they are bounded by a sharp margin, gently convex throughout. 
This aspect also reveals to us again a partial view of the prefrontals 
(Fig. 31, Prf.) with their postero-alar projections. The central point of 
interest, however, centers about the paraspheroicl in this region. It is 
here broad and elliptical, concave from before, backwards, and slightly so 
from side to side. An area of teeth occupy this space, conforming to its 
shape, though separated from its limiting margins all about by some 
two or three millimeters. These teeth are of various sizes, the smaller 
ones being arranged all the way round, externally, while they become 
larger and larger as we approach the mid parts of the space. They are 
beautifully enameled and rounded. Where the large ones, however, are REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
crowded together centrally, they assume hexagonal or perhaps pentag- 
onal forms. When they drop out and are lost, they leave quite a deep, 
conical pit or socket behind them. Posterior to this dental area, the 
parasphenoid lies horizontally, being convex from side to side, in order 
to conform with the lower surface of the cranium. Behind, it is forked, 
the limbs being carried backward to within a millimeter or so of the 
posterior margin of the basioccipital. Between them we find a trian- 
gular depression with its apex directed forward. Viewing the cranium 
from this aspect, its posterior third is broad and of a quadrilateral out- 
line, the figure being bounded in front by the postfrontals (Fig. 31, 
Ptf.); laterally by the squamosals, and behind by the ex- and basioccip- 
ital, opisthotics, and squamosals. Rising in the center of this space, 
mesially, is the portion formed principally by the prootics and basi- 
occipital, being overlapped by the parasphenoid. This contains the 
eye-muscle canal, with the braincase above it. Its form is well shown 
in the figures I present of the lateral and inferior views of the cranium 
of this fish. On either side of it occurs a deep conical indentation, about 
which the various foramina pierce the bone to enter the brain-case. 
These openings, and this great, blind, conical pit are bounded exter- 
nally by the facet, on either side, for the hyomandibular. 
The rear view of the cranium of Abula is an exceedingly interesting 
study, presenting conditions that I have never observed in any other 
fish. On the superior aspect of the cranium (Fig. 30 8. 0.) we saw how 
the supraoccipital was wedged in between the parietals. From this 
portion in the middle line, it throws backwards and downwards a 
stumpy, triangular crest, composed for its greater part of two parallel 
and vertical laminae, separated from each other by about a millimeter. 
On either side of this the bone extends horizontally for a little distance 
to meet the epiotics. These last elements may also be seen upon 
superior view (Fig. 30 Ep. 0.). They there articulate with the squamo- 
sals and parietals, and with the supraoccipital as just described. Each 
epiotic from this position, is extended backwards as a stout horizontal 
and triangular process, a peculiar tubercle being developed on its 
superior surface. Beneath, and anteriorly, the under surface of this 
process sends down a vertical plate, lying parallel to the median plane. 
These two plates inclose a general concavity on the posterior aspect of 
the cranium, which is partially divided in two by a vertical crest on the 
supraoccipital which again is directly continued by the crest formed 
through the uniting suture of the exoccipitals. The upper part of the 
base of this concavity is composed of the vertical portion of the supra-, 
occipital, while all the lower part is composed of the broad exoccipitals, 
the cranium being held and viewed with the frontals upwards and in 
the horizontal plane. Now, wedged in, in this concavity, on each side, 
and outwards, we observe what first appears to be a separate and 
nearly circular piece of bone, it being pierced by three foraininae. Towards 
the median line it articulates with the supraoccipital and exoccipital, 65 
THE OSTEOLOGY OF AMIA CALVA. 
while externally it meets the epiotic. Careful examination shows that 
this plate belongs to the squamosal. At the base of each vertical epi- 
otic plate is to be seen a stumpy process, formed by a separate segment 
of bone, which I take to be the opisthotic. It articulates with the epi- 
otic, exoccipital, and squamosal. On the outer side of each vertical 
epiotic plate there is another very deep concavity formed entirely by 
the squamosal, except such inner part of its entrance which is entered 
into by the vertical epiotic plate just mentioned. It is near the opening 
of this deep pit (1.25 cm) on the inner hand that we have the oppor- 
tunity to study the manner in which the squamosal furnishes the little 
circular plate that appears superficially in the larger concavity, as 
described above. 
The foramen magnum is of a cordate outline, with its base below. Tt 
is directed, that is the plane tangent to its margins, somewhat down- 
wards as well as backwards. Its boundary below is formed by the 
upper surface of the basioccipital condyle, while its lateral margins and 
’apex are furnished by a bone shaped like a little saddle, which strad- 
dles the exoccipitals (Fig. 29, c. v). This bone, but loosely united along 
its median line above, articulates with these last-mentioned segments 
throughout its entire anterior margin, and in the specimen in my hand 
is slightly movable. At its lower and outer angles are seen a minute 
pair, one on either side, of postzygapophyses. This bone fails to come 
in contact with the basioccipital, and were it removed the foramen mag- 
num would then be formed entirely by the basioccipital and exocci- 
pitals, though these latter would be without articular zygapophysial 
facets for the first vertebra of the trunk. Dr. Grill expresses the opinion, 
in which I concur, that this double bonelet is the neural arch of the first 
vertebra of the column. This being the case, it is important to compare 
it with the co-ossified vertebrae found in this situation in A mia. I would 
not care to do this, however, until in possession of a recent specimen of 
Albula as well as its young. The outline of the basioccipital condyle is 
pentagonal, and it is deeply and conically concave. A large elliptical 
foramen pierces the supraoccipital on either side beneath, at the angle of 
its horizontal and vertical portion. Two small foramina are also found 
on either side in the exoccipitals just before we arrive at the suture, 
where they join the aforesaid free neural arch just mentioned. 
This completes my description of the posterior view of the cranium 
of Albula, as far as 1 mean to carry it. I am well a ware that these bones 
may be differently construed, but the moment we do so it becomes 
necessary to have the various segments articulate among each other in 
a manner differing from the general rule they adhere to in the vast 
majority of cases among teleosts. To satisfy himself of this fact the 
reader has but to call the bone I have described as a neural arch of the 
first vertebra, the united exoccipitals, and the result will soon be evi- 
dent. We must remember, in this connection, that the facet for the REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
66 
atlas, supplied by the occiput in Amia, is upon a co-ossified vertebra. 
(See Part I.) 
Nearly all objects in nature are best seen, studied, and appreciated in 
direct lateral view, and to this aphorism the cranium of a fish offers no 
exception. This will at once be recognized in the case of our present 
subject the “Lady fish,” aside view of the parts already examined, which 
1 have endeavored to execute with great care, being presented in Fig. 
29, along with the greater portion of the palato-quadrate arch. The 
shape of the curiously formed ethmoid (Eth.) is now easily seen, and its 
relations with its neighboring bones better understood; while beneath 
it the vomer shows but slightly, though enough of it can be observed in 
order to expose the position of the series of minute teeth spoken of above. 
The prefrontal is seen to be enormously developed. It meets its fellow 
in the median plane, each one being pierced near this region by a large 
elliptical foramen. Between the anterior convex border of this bone 
and the ethmoid we find a vertical lamina of bone articulating as shown 
in Fig. 29 at Wa2. This element I take to be merely a plate of seini- 
ossified cartilage, though an examination of Albula in the flesh, on some 
future occasion, may force me to a change of opinion. The true nasals 
in the specimen must have been lost. The orbits are seen to be almost 
completely separated from each other by a thoroughly ossified inter- 
orbital septum, an extension forward of the co-ossified orbitosphenoids. 
(Fig. 29 Os.) This septum is very materially added to by the broad* 
vertical plate, afforded by the basisphenoid (ib. B. S.) 
This bone also sends upwards and outwards an osseous limb to artic- 
ulate with the alisphenoid (vis.). The three sphenoidal bones men- 
tioned surround the optic foramen, as shown in the figure. While the 
prefrontal completely forms the anterior wall of the orbital cavity, the 
frontal the vault, the parasplienoid the floor, we find, in addition to 
the bones we have mentioned, that the posterior wall is largely formed 
by the postfrontal and prootic. Altogether this cavity is a very thor- 
oughly circumscribed one, so far as its osseous boundaries are con- 
cerned. 
The posterior aspect of the postfrontal (sphenotie) assists the squa- 
mosal in forming an extraordinarily deep pit in the region to the rear of 
the upper and posterior angle of the orbit. This pit is bounded above 
by the squamosal and frontal, anteriorly by the alisphenoid and post- 
frontal, internally by the squamosal, which bone with the postfrontal 
forms its floor; behind, it opens along a longitudinal concavity of the 
squamosal. Immediately below this concavity we find the facet for ar- 
ticulation with the hyomandibular, also formed by the squamosal in 
part, its anterior moiety being constituted by the postfrontal—not an 
uncommon condition among the Teleostei. 
Tlie regions occupied by the basi- and exoccipital, the prootic and 
other bones, are so well shown in the figure as not to need any special 
description here. THE OSTEOLOGY OF AMIA CALVA. 
We are still further impressed with the marked departures from the 
ordinary fishes made by Albula in its skull when we come to examine 
such of the bones of the palatoquadrate arch as I have before me, for 
which I am also indebted to Professor Gill. One view of this arch I have 
drawn in connection with the lateral view of the cranium (Fig. 29); the 
other is an inner view of the same specimen, and awarded a separate fig- 
ure (Fig. 28). When this arch is snugly articulated with the cranium, 
the hyomandibular (if. Jf.) is nearly in contact with the postfrontal and 
prootic for its entire length, or rather as much of it as is opposite these 
bones; the same may be said for the remaining elements, the meta- 
pterygoidal and entopterygoidal margins meeting the opposed margin of 
the parasphenoid. Upon an inner aspect this brings the area of teeth 
found upon the entopterygoid (Fig. 28) opposite and at right angles 
with the similarly constituted teeth upon the parasphenoid. That teeth 
should occur exclusively upon the first-mentioned segment is a remarka- 
ble fact of itself and worthy of special note. Particular attention is invited 
to the symplectic (Sym.) of Albula, shown in these drawings, holding as it 
does a most unique position. Indeed, this may be said of all the bones 
in this arch ; the metapterygoid is thrown clear to the rear of the quadrate, 
while in Amia it reaches well beyond that bone. Both the entopterygoid 
and ectopterygoid are enormously developed. Wedged in between them 
posteriorly and above is a large mass of bone that appears to be devel- 
oped on the part of the first mentioned element. Where they meet at 
the apex anteriorly I find another irregular piece of bone, with a little 
process on its outer side. This element appears to be separately ossi- 
fied, but without a complete skull I could not say positively whether it 
be the palatine or not. It occupies about the proper position for that 
bone, and, everything considered, it would not surprise me to find it 
assuming any remarkable shape. A highly developed and prominent 
semiglobular facet is found on the upper third of the posterior margin 
of the hyomandibular, for articulation with the operculum. 
Of the cranium of Megalops.—The specimen of the cranium of this fish 
is also from the cabinet of Professor Gill, and from it I have made two 
drawings (Plate XIV, Figs. 33 and 34)—a direct lateral view and a pos- 
terior one. The specimen is evidently not a perfect one, though it is 
the best I could secure for the purpose, and my reasons for choosing it 
have already been stated above. In this particular specimen the basi- 
sphenoid is apparently missing, its median plate having been broken 
off, leaving the points of fracture distinctly visible. Again, either a 
single parietal plate or a pair of parietals have undoubtedly been lost, 
and when perfect individuals come to be examined I believe the space 
existing in Fig. 34 between the supraoccipital and frontals will be 
properly filled in by such a plate or plates. The rear view of this cra- 
nium is unaffected by these losses, as none of the bones mentioned 
would come in sight in this aspect. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
In Megalops the vomer is the most anterior bone of the cranium. 
Viewed from above, it presents a median crest with sloping sides, and 
is overlapped by a triangular process of the ethmoid. Below it is a 
broad semicircular plate, with a sharp spine directed backwards, which 
is mortised into the parasphenoid. Anteriorly this plate supports a 
raised elliptical disk, armed over its entire surface with exceedingly 
minute teeth (Fig. 34, Vo.). The ethmoid throws out on either side a 
curved and flattened process, directed outwards, downwards, and back- 
wards ; against the extremity of each rests an irregular prefrontal (Fig. 
34, Prf. Etli.). This region is completed by the anterior extremities of 
the frontal and parasphenoid as far as its bony walls are concerned, 
while its remaining parts are fashioned in cartilage. The rostrum of 
the parasphenoid makes an angle of 45° with the plane of its body. 
Its anterior extremity is dilated from side to side, and articulates with 
the vomer, as already described. The under surface of the rostrum is 
longitudinally concave, deepest near its middle third. Its upper sur- 
face is composed of two sides, each directed upwards and outwards; 
they meet for the entire length in the median line. The lower part, 
or body, of the parasphenoid is scooped out above to assist in the for- 
mation of the eye-muscle canal; its outer margins articulating with the 
prootics (Fig. 34, Pro.). Posteriorly the parasphenoid is sharply forked, 
but is not carried backwards quite as far as the basioccipital goes. 
The frontals (Fr.) are separated bones, divided by a median, and in 
the specimen rather an open, suture. Behind they overlap the squa- 
mosals on either side, while in turn they are beneath the hinder margin 
of the ethmoid in front. Their posterior margins are scalloped and the 
superficies of the bones above strongly sculptured. Either postfrontal 
develops a prominent lateral process; the extensive base supporting it 
so expands as to articulate with the squamosal and frontal above the 
alisphenoid internally and the prootic below. It also assists the squa- 
mosal in forming the anterior end of the hyomandibular facet (Fig. 34, 
Ptf.). A median tubular foramen passes longitudinally through the 
orbitosphenoid, below which it sends forward a peculiar little process 
as shown in the figure. This is carried backwards as a bony division, 
separating the alisphenoid, and forming the apex of the maigin of the 
optic foramen. The body of the orbitosphenoid articulates with a car- 
tilaginous plate anteriorly, while its sides, which are tipped upwards, 
inclose a space which we will devote our attention to further on. The 
alisphenoid« are large circular bones, separated from each other by the 
orbitosphenoid in the median line. They bound the optic foramen lat- 
erally and form the posterior wall for the orbits. There seems to be 
every indication that in life they are separated above from the frontals 
by cartilage, though they articulate by suture with the postlrontals 
and prootics (Fig. 34, As.). 
The squamosal is a very large and prominent bone in the cranium of 
this fish. Above, it forms a considerable share of the vault of the skull, 69 
THE OSTEOLOGY OF AMIA CALVA. 
articulating with the epiotic behind, and the frontal and spheuotic in 
front. (Sq.) Laterally it forms the hyomandibular facet, and enters with 
the opiothotic and prootic into the formation of a deep conical indenta- 
tion, immediately below the facet in question. It has a strongly marked 
and raised ridge, extending from its outer and posterior angle obliquely 
to the corresponding angle of the frontal (Fig. 34). 
The basiocvipital occupying its usual position, is much compressed 
from side to side, notwithstanding its centrum behind is very large, with 
raised periphery. Most of the antero-lateral region of the cranium of 
Megalops is made up of the pro otic (Pr. 0.). This bone is pierced by its 
usual foramina, and meets its fellow of the opposite side in the floor of 
the cranium. Upon the lateral view of this part of the skull, the most 
striking featureis a thin lamina of bone, with itsplane nearly parallel with 
the basioccipital, and formed not altogether unlike a diminutive hand. 
This appendage seems to be developed on the part of the opisthotic, but 
of its function I can say nothing until I am permitted to make a dis- 
section of a fresh specimen of Megalops. A posterior view of the cra- 
nium of this fish reveals to us its most extraordinary structure, and one 
that would not be suspected hardly from a direct lateral aspect; indeed, 
not at all, if the vacuity were filled in, where'I believe the parietals 
really belong. 
To arrive at a good description of the condition of affairs, as I find 
them here, it will be necessary for me to describe one or turn of the 
bones seen on posterior view, and first among these the supraoccipital. 
Viewed from above, this bone presents somewhat of an extensive sur- 
face, being greatly convex from side to side, while it is carried forward 
in the median line as a sharp process (Fig. 34, S. 0.), and behind we 
see developed a stunted, lamelliform “supraoccipital crest,” extending 
directly backwards, with a small foramen on either side of it. Behind, 
this bone is represented by a vertical plate wedged in between the epi- 
otics, a vacuity existing at its apex below. The epiotics are well shown 
in Fig. 33 (Ep. 0.), and the manner in which they articulate with the 
exoccipitals and squamosals (E. 0. and Sq.). Now upon the anterior 
aspect the supraoccipital and the epiotic on either side, chiefly the 
former bone, go to form a plowshare-shaped projection, that forms the 
hinder and upper part of the vault of the cranium. Beyond it lies 
a convex surface, in the specimen formed of dried membrane; this con- 
stitutes the next section of the cranial vault. Upon the outer side of 
either epiotic we observe a large elliptical opening; these lead into a 
capacious cavity that exists between the frontals, squamosals, and 
other bones of the roof above, and the true outer cranial vault, com- 
posed of the alisphenoids, prefrontals, squamosals, and other bones 
below. This cavity is irregularly wedge-shaped, its base being behind 
and its thin edge situated anteriorly. This latter part lies between the 
orbitosphenoids below and the frontals above. As we proceed back- 
wards the interspace becomes greater, and it is here bounded by the REPORT OF COMMISSIONER OF FISII AND FISHERIES. 
frontals above and the alisphenoid and postfrontals below. In this 
region, too, in the median line, we find that the alisphenoids and orbito- 
sphenoids contribute to form a bony stanchion, that is directed forwards 
and upwards for the support of the frontal plates which rest upon its 
apex. The alisphenoids are produced clear backwards to form a dome- 
like surface, convex outwards, that is the anterior roof of the cranial 
vault. In this the alisphenoids are assisted by the postfrontals on 
either side, and both of these bones can be seen through the apertures 
of this cavity behind (Fig. 33, As. and Ft/.). The sides of the roof ot 
the cranium are formed by an incurved surface on the part of each 
squamosal, while a somewhat similar surface, afforded by either exoc- 
cipital, completes the parietes of the brain case in the rear. 
The form of the exoccipitals, the method in which they articulate 
with the surrounding bones, and how they contribute to the formation 
of the foramen magnum, is all well shown in Fig. 3■5, where these 
bones are marked E. 0. A vagus foramen pierces each one on either 
side of the foramen magnum, while, owing to the fact that the exit tor 
the ojfiie nerves being so large, the parasphenoid can easily be dis- 
cerned through the latter opening (Fig. 33). The basioccipital forms 
the lower arc of the periphery of the foramen magnum, as shown 
in the figure. Its large articular facet is completely covered, through 
the very interesting fact that it is so far anchylosed with the first ver- 
tebra of the column that it is impossible to remove the latter in the speci- 
men without doing it injury (see Plate XIX, Figs. 33 and 3t, c. v.). 
This is particularly interesting when we recall what has been said above, 
iu regard to the co-ossified vertebra of Amia, found in this locality, as 
well as the suspicious condition of affairs in these parts in Albula vulpes. 
The suture between this vertebra in Megalops and the exoccipital is 
distinctly retained, and may be traced completely around the bone. 
Upon the upper side of this co-ossified or rather co-anchylosed vertebra 
are seen two circular pits, of some little depth and size. Dr. Gill states 
that these are intended to lodge the extremities of the neural arch. 
They are placed side by side transversely and about a millimeter apart. 
Two similar pits and similarly situated occur on t he under side of the 
vertebra. I am unable to pronounce upon these without first examin- 
ing a recent specimen of this fish. 
Far as Megalops is removed from Amia calva, I still find in this old im- 
perfect cranium from Professor Gill’s cabinet plenty of food for thought— 
with its suspicious-looking basioccipital vertebra, with its appropria- 
tion of at least one trunk vertebra, with its sculptured frontals and other 
bones raised above the cranium proper, with its more or less circular Mt- 
and orbito-sphenoids, and with the knowledge that a gular plate is found 
between the rami of its mandible. 
We now return to our more typical Teleostean, Micropterus salmoides, 
and discuss other bones of its skull that I have as yet not touched upon 
in this memoir. THE OSTEOLOGY OiT AMIA CALVA. 
As in so many other bony fishes, we find in this Bass a series of ir- 
regularly-shaped bonelets, circumscribing the lower boundary of the 
orbit. These are the suborbitals (Fig. 27, Sb. o.). They are seven or 
eight in number, the hinder one resting on the postfrontal, while the 
large anterior one, which, in common with other osteologists, I have 
termed the lacrymal, overlaps, when in position, the maxillary and pre- 
frontal (La.). On either side of the ethmoid, and what at first appears 
to be almost a continuation of this chain of bones, we observe another 
slender osseous element. This is the nasal. A mucus canal perfo- 
rates its substance for its entire length (Fig. 27, Na.). In designating 
these bones as the nasals, I am aware it disagrees with what Sir Rich- 
ard Owen has stated in his Anatomy of Vertebrates in the matter (Vol. 
I, pages 113 and 114), and must believe with Parker that “ the proper 
nasal (na.) is a small ossification on each nasal roof, external to the 
supraethmoid in its middle region ” (The Salmon, Morph, of the Skull, 
page 74). I must also believe, until some better observer corrects me, 
that the bone I have described as the ethmoid in Megalops and Albula 
is a single ossification in the adult, and the nasals of these forms I take 
to be missing in the specimens in hand. Resting on the forward end 
of the cranium in Micropterus we find a handsomely developed pair of 
premaxillaries (Fig. 27, Pmx.). Each bone has an ascending process in 
this region of its support, and when the two are properly articulated 
they form a graceful and nearly semicircular arch, the lower surface 
of which is thickly studded with very fine teeth. A rounded, lamelli- 
form process is also developed on the upper side of the limb of each 
premaxillary, about one-third the distance above its pointed extremity 
(Plate VIII, Fig. 22). 
The maxillary is a large bone, with expanded hinder extremity, on 
the upper border of which it supports an admaxillary (Figs. 27 and 22c). 
It is completely edentulous as in most other osseous lishes. Ante- 
riorly it does not meet its fellow of the opposite side, but develops at 
this end, internally a circular and vertical disk, with a raised facet to 
articulate with the cranium. Another elliptical disk is found at this 
extremity, directed outwards. It is for the maxillary process of the 
palatine to play on. The form of the palatine in Micropterus is well 
shown in Fig. 22, PI. This bone being firmly articulated with the 
nalato-quadrate arch, and the auxiliaries and premaxillaries being 
freely movable, the mechanism of these latter bones offers an in- 
teresting study. The manner in which they may move upon each other 
is easily seen in Fig. 22. This is still more engaging a subject in 
those fishes with protractile snouts, of which there are many genera. 
In Micropterus the opercular group of bones is very well developed 
(Fig. 27, aud Plate XIII, Fig. 32, Op., S. Op., Pr. 0., and I. Op.). The 
operculum is a beautiful scale-like plate of bone, the largest of the four. 
In outline it is an irregular quadrilateral, with a reinforced border on 
its anterior margin, which is so fashioned aud strengthened at its upper REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
and anterior angle as to form a proper enlargement to support the 
articular facet for the hyomaudibular. Viewed from without, its lower- 
border overlaps for a couple of millimeters the suboperculum. This 
latter bone is shaped as shown in Figs. 27 and 32. Anteriorly it de- 
velops a pointed and upturned process, that lies between the lower- 
angle of the operculum and the upper angle of the interoperculum. 
The interoperculum has a quadrilateral outline, with theangles rounded 
off*. Externally it is well overlapped by the preoperculum, and is at- 
tached to the mandible by ligament, while internally the epiliyal and 
interhyal of the hyoid arch rest against it. In texture these three 
bones of the group are semitransparent and exquisitely marked with 
radiating and wavy concentric lines. 
The preoperculum overlies all the other opercular bones, while it itself 
is overlaid by the hyomaudibular above and the quadrate below. It is 
roughly crescentric in form, being carried to a gradually tapering point 
above, and strengthened throughout its entire length by a raised ridge 
of bone. On its inner aspect the lower limit of the hyomandibular, the 
interhyal, and the symplectic rest against it (Fig. 32). 
It has been said that the opercular bones are but modified, or rather 
transformed, branchiostegal rays. 
Situated beyond the opercula we discover another arcade of bones; 
this consists, from above downwards, of the hyomandibular, symplectic, 
and quadrate, the chain constituting the suspensorium. They con- 
nect, in Micropterus as in the osseous fishes generally, the cranium 
with the lower jaw (Figs. 27 and 32, S. M., Sym. and Qu.). By the 
intervention of the interhyal, the hyomandibular has also suspended 
from its lower extremity the hyoid arch, and its upper and poste- 
rior angle, as we saw above, also articulates with the operculum. 
The hyomandibular is compressed from side to side, expanded above, 
to be gradually drawn down to a blunt point below, where it is united 
through a common cartilaginous bridge with the apices of the interhyal 
and symplectic. This latter element is wedged in between the quad- 
rate and preoperculum, with the metapterygoid resting against its an- 
terior border, it being merely a small bone that has been segmented off 
from the hyomandibular. 
The quadrate is here, as is usually the case among fishes, a triangular 
bone of some size, articulating with the mandible at its lower angle 
(Fig. 27, Qu.). Against the upper half of its anterior border, by a very 
close suture, the ectopterygoid is placed, forming a part of the con- 
nection of the next arch beyond with the suspensorium. Upon the cra- 
nium the hyomaudibular articulates with the postfrontal and squamo- 
sal in a long, narrow, longitudinal facet. 
Tlie arch next beyond the suspensorium is the pterygopalatine arch. 
It is made up of the metapterygoid, the ento- and ectoptergoid and the 
palatine. This last element I have figured and sufficiently described 
above. In a great many fishes the palatine is movably connected at 73 
THE OSTEOLOGY OF AMIA CALYA. 
the anterior extremity of the arch to which it belongs. The metaptery- 
goid (Fig. 32, M. Ft.), a flattened and irregularly shaped bone is wedged 
in between the hyornandibular and quadrate, and firmly establishes 
the connection of the two arches at this extremity. It overlies also a 
thin scale-like process throwli out on the part of the ectopterygoid, just 
opposite the angle this bone makes above its articulation with the 
quadrate. The ectopterygoid is a bent and narrow strip of bone that 
directly connects the quadrate with the palatine. It forms the outer 
margin of the floor of the orbit, which is chiefly made up of the ento- 
pterygoid. Both the palatine and ectopterygoid support a dense area 
of very fine teeth upon their lower surfaces. The entopierygoid is a 
beautiful sheli-like bone which is overlapped by the palatine anteriorly 
and the metapterygoid behind. It is bent upon itself at about its lower 
third towards the median plane, and thus forms the greater part of the 
floor of the orbit by its upper surface, and by its lower the roof of the 
mouth. The entopterygoid is quite transparent, and for some little 
distance from its outer margin marked by wavy and delicate concen- 
tric lines. 
Although the bones just described are so intimately connected with 
the quadrate, I prefer to call this arch, as I have done above, the 
pterygo palatine, considering the quadrate as the property of the sus- 
pensorium. It is often termed, however, the palato quadrate arch, and 
I took occasion to use this term in the first part of this paper. 
Of the Hyoid and Branchial Arches of Micropterus.—Our large-mouthed 
black bass offers us very little that differs from the more typical Teleos- 
teans in the skeletal parts of i: s respiratory apparatus. From the lower 
end of each hyomamlibular there is, as we saw above, suspended a small 
rod of bone, the interhyal (the stylohyal of many authors) To these is 
articulated, on either side, a broad triangular piece, the epihyal (Fig. 
32, E. hy.), which in its turn connects with the larger and longer piece, 
the ceratohyal. The connection between these twro lattvr elements is 
very much strengthened by a longitudinal lashing of bony fibers on the 
inner aspects over the joint, the bones themselves being quite com- 
pressed and flattened plates of a form shown in the figure. The cerato- 
hyals, the anterior pair, meet in front in a ligamentous symphysis, over 
which ride, side by side, two other separate elements, the hypokyals {H. 
hy.). These are broadly conical in form, with their apices drawn out 
into blunt processes, which are directed upwards and backwards. Best- 
ing upon the liypohyals above is an azygos bone about a centimeter 
long (in a bass that would weigh three pounds), which is the glosso- 
hyal (Fig. 27, G. hy.). it is a flattened bone, shaped somewhat like 
the vertical section of an hour-glass, it being the part of the skeleton 
which supports the soft parts of the tongue. This bone has also been 
called the os lingualc. It may be absent in some of the true bony fishes. 
In the specimen I have in my hand we see on the outer aspect of the 
epihyal, just above its lower and near its anterior border, two large and REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
curved branchiostegal rays, which in life are held in this position by lig- 
ament. The hinder and larger one is possessed of quite a blade-like 
extension, and the bone, like the rest of the series, is gently curved up- 
wards. Two more branchiostegal rays are attached in a similar manner 
to the ceratohyal, the four bones being placed at about equal distances 
apart. The series of branchiostegal rays progressively increase in size 
from before backwards, the anterior ones being the most abruptly 
curved. The next two rays in order are attached to the lower margin 
of the ceratohyal, and I am under the impression that I have dissected 
specimens where a seventh ray has existed that was attached in order, 
beyond these, just within this border. As we know, the branchiostegal 
rays support a membrane of the same name, which forms sort of an 
auxiliary gill-flap. 
Lying in the median plane, posterior to, but attached by ligament to 
the symphysis of the cerato-hyals, we find a plate of bone, that in the 
living fish separates the sternohyoid muscles. This bone is of a tri- 
angular outline, with its apex forward, a part of which bears a dilata- 
tion and superior osseous loop for a greater ligamentous attachment. Its 
lower margin is transversely expanded, and the plate is further strength- 
ened by the development of an osseous rod that runs longitudinally 
through its center. This azygos plate is the urohyal, and is peculiar to 
fishes. In life it lies between the sternohyoid muscles, and is not al- 
ways present where a glossohyal exists. 
Aside from this urohyal and the branchiostegal rays, the bones we 
have been thus far examining constitute the hyoid arch, and this Bass 
presents it in what may be said a typical form for fishes, if anything can 
be adopted as a standard in form in a class where all the structures 
vary so in shape. 
The relation of the various bones of the piscine skull and their func- 
tions, when we come to compare them with the homologous elements in 
the higher animals—man, for instance—has always presented to my mind 
one of the most interesting subjects in anatomy. Here in our specimen 
we have the hyoid arch, supporting, on either side, a series of branchi- 
ostegal rays. These rays constitute the skeleton of an organ of defense to 
the respiratory apparatus. It is believed by some that the opercular 
bones are modified branchiostegal rays, and these in their turn form 
the lateral osseous Kail of defense to the gill chamber, also the respiratory 
apparatus. The operculum articulates with the hyomandibular of the 
suspensorium, which bone is said to be the representative of the incus 
of the human ear, while the lower bone, the quadrate, of the suspenso- 
rium, is a segmented portion of the malleus, another of the auditory os- 
sicles in man. Now, in its turn the quadrate articulates with the man- 
dible or lower jaw, a bone in one way subservient to the digestive appa- 
ratus. 
Lying in the angle formed by the limbs of the hyoid, we find the 
branchial arches. The arrangement of these in Mieropterus is so like it THE OSTEOLOGY OF AMIA CALYA. 
is found in Perea, and the arches in this latter fish have become so well 
known both to layman and ichthyotomist, through the many reproduc- 
tions made of Cuvier’s old figure, that I have not thought it necessary 
to present a figure of this part of the skeleton to illustrate our subject. 
In the specimen of the bass in my hand, I find but two of the copulm or 
basibranchials ossified. We remember that three of them ossify in the 
perch. Then follow on either side the five pair of segmented branchial 
arches common to the vast majority of the class; these bear the dentig- 
erous patches on their upper surfaces—the gill-rakers being found 
farther back and on the outer pair only—while below they support the 
gills proper. 
My collection contains specimens, however, where all three of the 
basibranchials are well ossified, and teeth appear on the upper surface 
of the rear one in two circular patches. The ultimate gill-raker is T- 
shaped, the horizontal bar being applied to the outer side of the arch. 
The outer pair of branchial arches are each in two segments—a long, 
posterior, and interiorly grooved pair, and an anterior or shorter pair 
that articulate with the middle of the indented sides of the mid-basi- 
branehial. These latter are bent at a right angle, the long.limb being 
continuous with the hinder segment; the short one, which is quite 
broad, is the part that meets the basibrauchial. This description an- 
swers very well for the second branchial arch. The anterior segments 
of the third arch are much broader, and lie on either side of the ulti- 
mate basibranchial, while the fourth arch has no anterior segments; 
the posterior ones, or those that correspond to them in the other arches, 
touch each other in the median line. 
The inf rap h a ryngea l bones are broad, thickly studded with teeth on 
their superior surfaces, and drawn out into sharp extremities behind. 
Supported in the usual manner through the means of ligaments by the 
upturned portions of the arches, and lying beneath the cranium—the 
suprapharyngeal bones—are also thickly beset with teeth. 
OF THE MANDIBLE OF MICROPTERUS. 
We saw that the lower jaw of Amia ossified on either side from quite 
a number of centers; that it developed a large splenial and other sep- 
arate elements. This is not the case, however, with the large-mouthed 
black bass. In this fish, as in many other Teleosteans, each ramus is 
composed in the adult of but three distinct pieces. These are the den- 
t-ary, the articular, and the angular (Plate III, Fig. 15, I). Art. and 
Ang.). Owen tells us that “in both Sudis and Lepidosteus there is 
superadded a small bony piece, answering to the surangular of Keptiles.” 
(Anat. Verts, vol. i, page 123.) 
The articular of Micropterus (Art.) consists of a vertical and a horizon- 
tal portion, the latter being attached to its posterior half, and is ex- 
tended backwards to bear the concave lunar facet to articulate with the 
quadrate. The articular surface of this facet, although on the liori- REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
zontal portion, of course, looks almost directly upwards. The upper 
aspect of this plate is marked by wavy lines, five or six in depth, that 
run round the bone parallel to its outer margin. Passing obliquely 
through the center of the bone is a mucus canal, the posterior opening 
of which is a circular foramen placed at the back of the articular pro- 
cess. The anterior opening is flattened and is opposite a similar canal 
that passes through the body of the dentarv. The vertical portion of 
the articular is of a triangular form, and contains, in a canal in its sub- 
stance, open on the inner aspect, running longitudinally at its base, the 
Mecklian cartilage (Fig. 15 M.c.). This cartilage passes into the deutary 
which ensheaths it nearly to the symphysis. The posterior border of 
the vertical plate of the articular is re-enforced by a thickened and 
raised rim, the laminated portion being beautifully marked by white 
lines running parallel to its superior margin. Radiating lines are also 
carried out to this border from the angle formed by its thickened pos- 
terior border and its line of union with the horizontal portion. 
The inner posterior angle of the horizontal portion of the articular is 
completed by a separate piece of bone. This is the angular. It is tri- 
angular in form and unites with the articular in a roughened suture. 
This union is not so firm but that the piece comes away during ordi- 
nary maceration. 
The two dentary pieces join each other anteriorly in the median plane 
in quite a firm symphysis. Thus formed, the entire bone constitutes 
the major part of the mandible, its superior border being thickly stud- 
ded with rows of teeth. These rows become fewer in number, and 
the teeth progressively smaller as we proceed backwards, and they 
cease to appear within short distance of the posterior projections be- 
hind. Each dentary element, posteriorly in the vertical plane, is deeply 
notched by a triangular indentation (Fig. 15). At the anterior apex 
of this triangle enters the Mecklian cartilage. The limb below, of this 
fork, lies in the horizontal plane, constituting the hinder half of an ellip- 
tical plate of the dentary, similarly situated. It is through this part 
that the mucus canal is ensheathed, and into it on the inferior surface 
open three foramina placed a short distance apart. Other foramina 
pierce each deutary element on the outer aspect, half way between the 
symphysis and the apex of the postero superior process. They are for 
the passage of vessels and nerves. 
Huxley, in speaking- of tlie mode of development that takes place in 
this region, tells 11s that “two ossifications commonly appear near the 
proximal end of Meckel’s cartilage, and become bones movably articu- 
lated together. The proximal of these is the quadrate bone found in 
most vertebrates, the malleus of mammals; the distal is the os articulare 
of the lower jaw in most vertebrates, but does not seem to be repre- 
sented in mammals. The remainder of Meckel’s cartilage usually per- 
sists for a longer or shorter time, but does not ossify. It becomes sur- 
rounded by bone, arising from one or several centers, in the adjacent THE OSTEOLOGY OF AMIA CALVA. 
membrane, and the ranins of the mandible thus formed articulates with 
the squamosal bone in mammals, but in other vertebrata is immovably 
united with the os articuJare. Hence the complete ramus of the mandi- 
ble articulates directly with the skull in mammals, but only indirectly, 
or through the intermediation of the quadrate, in other Vertebrata” 
(Anat. of vertebrated animals, p. 28,29). Many of the Teleostei have 
various muco-dermal bones attached to, or connected with the skull, 
such as the chain of u supertemporals ” that overarch the temporal fossa 
in some fishes. The most important of these in Micropterus, a pair on 
either side, I propose to call the supralinear ossicles (si), as they overlie 
the anterior end of the lateral line. The largest and most external of 
these is shaped like a T, the ends of the horizontal portion resting on 
the squamosal on one hand, and the posttemporal on the other. The 
vertical limb is directed inwards and a little forwards, having attached 
to it by ligament the second piece, directed still a little more anteriorly. 
In the living bass these bones are easily detected, lying just beneath 
the skin in the lateral line as it arches over the temporal region. 
OF THE SHOULDER GIRDLE OF AMIA CALVA. 
My description of the girdle of Amia will be presented pari passu with 
that of Micropterus salmoides, the Teleost we have chosen for comparison 
in the skull as given above. The nomenclature of the various segments 
of this part of the skeleton is a matter of great importance, and without 
entering into any discussion upon this point, I propose here to adopt 
that of Professor Gill, as set forth in his Arrangement of the Families 
of Fishes, published by the Smithsonian Institution {November, 1872). 
Dr. Gill very tersely gives his reasons for departing from the older au- 
thors on this subject in the introduction of this valuable and classical 
paper. It is not necess »ry for me to repeat his remarks here, as they 
are now well known to ichtliyotomists generally, having been in the 
hands of scientists for many years. 
As the two tables Dr. Gill presents, however, are of great value, 
and will add so much to my remarks in the present connection, it 
gives me much pleasure to introduce these here. This eminent ichthy- 
ologist first treats of the girdle in Dipnoans, and says in review that 
11 the homologies of the elements of the shoulder girdle of the Dipnoi 
appear then to be as follows”: 
Nomenclature adopted. 
Owen. 
Parker. 
Gunther. 
Humerus. 
Humerus. 
Humerus. 
Forearm. 
Coracoid (or Paraglenial). 
Scapula. 
Ectocoracojd (or Coracoid). 
1 Coracoid. 1 
Scapula. 
Supraclavicle. 
Clavicle. 
Humeral cartilage. 
| Coracoid. 
Sternum. 
Posttemporal. 
J i 
Scapula. 
Epicoracoid. 
Post t emporal. 
Median cartilage. 
Suprascapula. 
Iii this table I have omitted certain foot notes and quotations con- 
nected with it. As to 11 The Girdle in other Fishes ” Dr. Gill remarks REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
that “ the homologies of the elements of the girdle of Dipnoans with 
those of other fishes, and the added elements in the latter will be as 
follows ”: 
Cuvier. 
Owen. 
Gegenbaur. 
Parker. 
Actinosts. 
Os du carpe. 
Carpal. 
Basal stiickeder Brust- 
Brachial. 
flosse. 
Coracoid 
or Paeaglexial. 
Simple in Dipnoi and Ganoidei. 
Hypercoracoid. 
Kadial. 
Dina. 
Oberes Stuck (Scapu- 
Scapula. 
lare). 
Mesocoracoid. 
Troisiemeos de l’avant 
Humerus 
Spangcn stuck. 
Precoracoid. 
bras qui porte le na- 
geoire pectorale. 
Hypocoracoid. 
Cubital. 
Radius. 
Vorderes Stiick (Pro- 
Coracoid. 
coracoid.) 
Proscapula. 
Humeral. 
Coracoid. 
Clavicula. 
Clavicle. 
Scapula. 
Ectocoracoid. 
i 
Differentiated only in Dipnoi. 
Sternum. 
Differentiated in Dipnoi. 
POSTTEMPORAL ELEMENTS. 
POSTTEMPORAL. 
P O STTK ROTE M P 0 R AL. 
Te LEOT KMPORA I.S. 
Supra scapulaire. 
Scapnlaire. 
Os coracoidieu. 
Suprascapnla 
Scapula. 
Clavicle. 
Sapraclaviculare (a). 
Supraclaviculare (&). 
Accessorisclies Stuck 
Posttemporal. 
Supraclavicle. 
Postclavicles. 
Among Teleosteans, as a rule, the posttemporal, a forked bone (Plate 
VTII, Figs. 23, 24 Pst. T.), has its inner limb resting on the epiotic, 
and its outer one resting against or articulating with the pterotic. In 
some fishes, as the Cats, this limb comes lower down on the side of the 
cranium. 
The posttemporal of Amia, although it has on side view (Fig. 24) very 
much the appearance of this bone in Micropterus, this is by no means 
the case on superior view. In the Ganoid the bone is much spread out 
horizontally and sculptured for a narrow strip just within its external 
border, like the “cover-bones” of the skull. Moreover, its inner limb, 
in Amia, articulates with the epiotic, while its outer and lower one, a 
rounded prong, meets the opisthotic. 
The posttemporal in Micropterus is placed much more in the vertical 
plane; the anterior extremity of its somewhat com pressed and longer 
upper limb rests on the epiotic, while its lower and shorter limb abuts 
against the pterotic. A process in both these fishes projects backwards 
from this fork of the posttemporal, against the inner aspect of which 
the posterotemporal articulates. This latter is a scale like element, with 
rather a rounded superior head. Its posterior border is deeply notched 
in Amia, and in both cases its flat surface is nearly parallel with the 
median plane (Figs. 23 and 24, Psto. T). Resting on the inner surface 
of the lower fifth of the posterotemporal in Amia, we see the upper teleo- 
temporal and the superior part of the vertical portion of the proscapula. 
This arrangement is far different in Micropterus, where the teleotemporals 
do not come in contact with the posterotemporals at all. The teleotem- 
poral of the Mudfish is of a quadrilateral outline, and this Ganoid is 
without any lower teleotemporal (Fig. 23 T.). THE OSTEOLOGY OF AMIA CALYA. 
In Micropterus there are two of these bones, an upper and a lower 
one, attached to the other elements of the girdle by ligaments. The 
upper piece is a scale-like bone parallel to the median plane, while the 
lower segment is a straight spine resting upon the inner aspect of the 
entire length of its anterior border (Fig. 23 T ). This lower teleotem- 
poral was regarded by Carus as a displaced iliac bone. These teleotem- 
porals of the bass rest against the coracoids, and above the proscapula 
(Fig. 23). This latter element in Amia presents for examination a ver- 
tical portion, which has a strong process developed, directed upwards, 
at its antero-superior angle, a feature it holds in common with Microp- 
terus. Now, the outer aspect of this vertical portion is sculptured in 
Amia like the opercular bones, while in the bass it is marked like its 
own opercular bones, with white, wavy lines and radiations. 
The proscapula of Amia next sends off anteriorly from its vertical 
plate, nearly at right augles, a longer and broader portion. This part 
is pointed at its further end where it articulates with the fellow of the 
opposite side by ligament. Its upper surface is gently convex, and its 
inner margin is fortified by a raised rim, directed downwards. This 
rim, similarly situated, becomes a prominent feature in Micropterus 
(Fig. 23), and the coracoids articulate at its lower edge. They occupy 
nearly the same position in Amia, but here they have become com- 
pletely amalgamated and are represented only in cartilage (Yn.). Mi- 
cropterus lacks a mesocoracoid, but both the liyper- and hypocoraeoid 
are thoroughly developed. The hypercoracoid is perforated about its 
middle by an elliptical foramen (Fig. 23, Hyp. c.), which is met in many 
other Teleosteans. Above, this bone articulates with the proscapula, 
as described above; anteriorly it articulates with the hypocoraeoid 
(Ryo. c.), lying in the same plane, while below it articulates with three 
of the actinosts; the fourth and largest of these bones articulating 
with the hypocoraeoid. This latter bone throws forwards a long, lamel- 
liforin spur that reaches far forwards on the under side of the proscap- 
ula. It shows a rounded notch behind, just anterior of the facet for 
the lower aetinost. There are four actinosts in Micropterus, shaped like 
little dice-boxes, and forming a graded series as regards their size. 
From their hinder ends spring the sixteen rays that go to form the pectoral 
Jin (Plate XIY, Fig. 35, Ast. Pf.). I find nine actinosts in the carpus of 
Amia, composed of very elementary bone, with dilated posterior ends, 
to which are attached the twenty-two rays of the pectoral fin. We 
cannot see all of these in Fig. 24, because the view does not admit of 
it, but they are correct in Fig. 35. Delicate markings encircle These 
rays for their entire length, commencing a short distance beyond their 
anterior ends. 
These members, after passing backwards for about half their dis- 
tance, divide in two, the forks keeping close side by side and one above 
the other. This phenomenon is repeated once more before arriving at 
the posterior margin of the fin. A similar splitting of the fin rays REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
80 
obtains also in the Mudfish. Here, too, the rays, if maceration is car- 
ried to excess, cleave in twain longitudinally, but as this can be studied 
to better advantage in the caudal rays of this Ganoid, I defer saying 
anything more about it until that part comes to be described. 
In Micropterus the apex of the united pelvic bones are inserted pos- 
teriorly into the angle formed by the articulation of the proscapulae. 
The pelvic bones are situated, as we shall see further on, far back in 
Amia, and differ very much in their general character. 
Upon the outer side of each proscapula in Amia are found a pair of 
very curious-appearing scales, composed apparently of a toughened 
membrane, marked in an irregular manner by lines of semi-osseous 
materia], that require the aid of a lens to properly study. These pecu- 
liar affairs are attached loosely to the sides of the proscapulae, but up 
to the present writing I am not aware that any physiologist has ad- 
vanced a theory as to the original function of these appendages. They 
have no evident use now. In referring to these interesting structures, 
Dr. Wilder says that04 “upon each side of the copula, or isthmus, which 
connects the shoulder-girdle of Amia65 with the hyoid arch, there are 
two appendages which are rarely mentioned by authors, and whose 
nature appears to be undetermined.”66 
‘ ‘ Historical sketch.—Accord i n g to D u meri 1,67 these a ppen dages are wh at 
Linmeus referred to in the following phrase, to which zoologists who 
have spoken of Amia do not appear to have attached a definite sig- 
nificance: Gula ossiculis, scutifonnihus, e centra striatus. Valenciennes 
supposed that he was impressed by the appearance of the brauchioste- 
gal rays, which form on each side a sort of striated plate; but in the 
phrase cited reference is evidently made to the two small dentated 
pieces of which I am speaking, and which is easy to see. I have also 
found them mentioned by Stannius.” With further quotation from 
Dumeril, the doctor says, “ The appendages are not mentioned in 
Franque’s description of Amia, nor in the monographs or systematic 
64 Wilder, Burt'G., on the Serrated Appendages of the Throat of Amia, Proc. Amer. 
Assn, of Science, 1876, page 259. 
65Amia is a fish found living in the Mississippi River and its tributaries, and in the 
great lakes. It attains a length of two feet, and is called by fishermen “mudfish,” 
“dogfish,” and “lake-lawyer.” Under the tip of the lower jaw is a movable plate, 
which does not exist in any other fresh-water fish of America. The adult male has a 
circular dark spot at the base of the tail (Jordan, 23, 306). Amia is now usually re- 
garded as a ganoid, and its brain closely resembles that of Lepidosteus (the gar- 
pike); but it seems to be, as remarked by Gill (10), the “most teleosteoid” of that 
group. [This foot-note is from Dr. Wilder’s article.] 
661 regret to say that it proved to be impracticable to reproduce Dr. Wilder’s figures 
in his very instructive plate. 
671 have omitted, in this long but important quotation from Wilder’s paper, the 
figures which this author gives that refer to the bibliographical table at the end of 
his article. Those who wish to refer to the authorities quoted will have to turn to 
the Proceedings containing this list. So short is Dr. Wilder’s paper, and yet his ob- 
servations are so valuable in the present connection, that I have incorporated them 
quite extensively, a fact that the reader no doubt will appreciate. THE OSTEOLOGY OF AMIA CALVA. 
works of Agassiz, Cuvier, Cope, DeKay, Gill, Gunther, Huxley, Jordan, 
Muller, Owen, Bolleston, or Vogt.” 
With regard to their location and general appearance, this author 
states that “ in the adult Amia there are two appendages on each side. 
They are usually concealed from view by the operculum; but the tipcf 
the hinder one sometimes projects beyond the operculum at a point a 
little above the base of the pectoral fin. The anterior appendage is 
about 2 centimeters long, and its anterior extremity is a little more than 
half its length from the union of the isthmus with the hyoid arch. Its 
hinder end is nearly opposite the medium tip of the shoulder-girdle. It 
is wholly superficial, and its hinder border projects but slightly beyond 
its attachment. The posterior appendage is about twice the length of 
the anterior, and consists of three portions: a short triangular root just 
beneath the skin; a short but broad base, the deep surface of which is 
continuous with the skin; a long free portion, which gradually tapers 
backward to the tip, which is less than lmm wide. The root lies to the 
mesial side of the posterior extremity of the anterior appendage, but 
there is a distance of nearly 2mm between them. The posterior append- 
age inclines dorsad, and rests quite closely against the adjacent surface 
of the shoulder-girdle. 
“Neither has any direct connection with bone. The attached sur- 
faces rest upon the muscles which constitute the isthmus, but do not 
appear to be attached to them. While observing living Amias with ref- 
erence to their respiratory function I never saw any movement of these 
appendages. The thickness of the posterior one is about \mm. It is 
quite flexible during life and while moist, but becomes more rigid when 
dried. 
“ The free surfaces of both appendages are corrugated in the adult. 
The general direction of the ridges and furrows is across the length of 
the surfaces obliquely forward from the dorsal toward the ventral bor- 
der. The ridges are more or less wavy in outline, and present irregu- 
larities of direction and arrangement, especially toward the tip and 
ventral border of the posterior appendage. But the distance between 
any two ridges is quite uniform; the number of ridges being about 18 
to the centimeter upon the anterior appendage, and about 12 upon the 
posterior. The transverse ridges do not always reach the ventral bor- 
der upon the anterior two-thirds of the posterior appendage; the ventral 
third of the surfaces is in some cases nearly free, but may present one 
or more ridges running nearly parallel with the border, or more often, 
especially on the inner surface, there may be a series of short ridges 
trending dorsad and forward from the lower border to meet the dorsal 
series at open angles. 
“ The anterior slopes of the ridges form an angle of about 45° with 
the surface5 but the posterior slopes are nearly perpendicular. The 
crests are projected backward as numerous fine teeth which are barely 
visible to the naked eye.” REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
This author then proceeds to give an interesting account of the de- 
velopment of these appendages, and in the matter of structure says 
they “ consist mainly of fibers running longitudinally. I have not yet 
examined them under the microscope.” The doctor is under the im- 
pression he has detected homologous structures in Lepidosteus, but as 
to their function he remarks that u I am not aware that any use has 
been assigned to these appendages, and I have no suggestion to offer. 
The anterior is evidently passive. The posterior, even if voluntarily 
movable by the fish, is too flexible for offense, and is, moreover, covered 
by the operculum,” and with regard to morphological significance u un- 
less some function can be assigned to these appendages the conclusion 
that must naturally suggests itself is that they are remnants of organs 
which had greater size and performed some function in more or less 
remote ancestors of Amia. The position and general appearance of the 
posterior pair are not wholly contradictory of the idea that they may 
have been accessory branchiae; but this could hardly be surmised re- 
specting the anterior pair, or the supposed homologous parts of Lepidos- 
teus. The appendages should be examined in fossil Amia and Lepidos- 
teiis, and in other extinct Ganoids ; likewise should careful search for 
them be made in all living Ganoids, and in the Teleosteau genera Elops 
and Megalops, which possess some points of resemblance to Amia.” 
The opportunity has never been offered me to examine either of these 
latter forms with the view of searching for these structures, and at the 
present writing I am aware of no one who has thrown any further 
light upon this subject since Dr. Wilder made the above observations. 
OF THE PELVIC BONES AND VENTRAL FINS OF AMIA. 
In speaking in a general way of these structures, Professor Huxley 
remarks, that “ In all Elasmobrauchs and Ganoids, and in a large 
proportion of the Teleosteans, the pelvic fins are situated far back on 
the under side of the body, and are said to be “ventral” in position ; 
but, in other Teleosteans, the ventral fins may work forward, so as to 
be placed immediately behind, or even in front of the pectoral fins. In 
the former case they are said to be “thoracic,” in the latter “jugular.” 
(Anat. Yert. Animals, p. 39.) These pelvic bones in our subject are 
quite well ossified, and hold a typical “ ventral ” position. (Plate X., Fig. 
26.) They are in two distinct pieces, each piece being shaped like a 
paddle, with the blade directed forwards. In life they lie side by side 
just beneath the skin, with the expanded blades in the horizontal plane. 
Their anterior extremities are cut square across, while posteriorly they 
are enlarged so these aspects present an elliptical face in each case. 
In a specimen of Amia with a vertebral column 30 centimeters long, I 
find the pelvic bones each to measure 2£ centimeters in length. So far 
as this description goes it agrees very well with these parts, as they are 
figured and described by Franque, but I find other structures here that 
apparently are not referred to, in either way, by this anatomist. Xow, 
we discover behind each pelvic bone in Amia and articulating with the THE OSTEOLOGY OF AMIA CALVA. 
posterior elliptical facet described above, another bone of a conical 
form, and about one-half a centimeter long. This element seems to 
take the place of the combined actinosts of the pectoral limb. Again, 
the rays of the ventral- fins are arranged in a peculiar manner; these, 
which seem to number from seven to eight in an adult specimen, are 
split as they are in the pectoral rays. The ends thus divided are held 
well apart in order to allow the separate conical piece of bone to be in- 
serted between them. As in the pectorals, too, these ventral fins are 
44branched” as they approach their posterior terminations. In form 
each fin is quite acute and the outer ray is the longest. 
Among the Teleosts the pelvic bones not only vary in position, but, as 
we might readily imagine, vary almost infinitely in regard to their rel- 
ative size and shape. Indeed, it would be a difficult thing to convey 
any adequate conception in such an essay as this, of these various forms. 
They are as numerous, nearly, as the species themselves. These bones 
are never attached to. the vertebral column as we find them in verte- 
brates above fishes. (Owen.) 
In Micropterns salmoides they are represented by two separate and 
symmetrical bones, that articulate with each other mesially, by their 
inner edges. When thus united they form an elongated isosceles tri- 
angle, with its apex held by ligament iu the entering angle behind the 
proscapulm. The outer borders develop a raised rim, and the planes 
of the surfaces contributed by the two bones superiorly, on either side, 
look upwards and outwards, the reverse being the case, of course, be- 
neath. The postero-external angles, as well as the hinder border, is 
thickened and undulating for the articulations of the heads of the ven- 
tral fin rays. There is, also, a characteristic process developed mesi- 
ally on this border, into which each pelvic bone takes an equal share. 
Above, it is bifid, being directed upwards and backwards, and com- 
pressed anteroposteriorly; below, it is peg-shaped and directed in the 
same degree forwards and downwards. 
I fail to find any bony nodules, representing the actinosts, between 
the ventral fin rays and the pelvic bones in this fish; and the rays 
themselves seem to be constructed upon the same plan as the pectoral 
ones, being retained in their positions by firm ligaments and the skin. 
The outer one, however, on either side, differs materially in form, being 
spoon-shaped, with the concavity a'gainst the next ray on its inner side. 
It also develops an inturned process, which curves over the next two or 
three rays. This double arrangement seems designed to strengthen 
the inner rays, and assist to keep them in their position. 
OF THE VERTEBRAL COLUMN, AND SKELETON OF THE REMAINING 
PARTS. 
Fias. 14, 25, and 26. 
Among the general characters of this part of the skeleton we know 
that “ the vertebral column of fishes can only be divided into two re- REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
84 
gions, the body and the tail. They are distinguished from each other 
by the characters of the inferior processes of the vertebrae, while the 
upper arches are connected with the vertebrae in the same manner 
throughout; and are generally by the possession of 
median (spinous) processes. In the region of the trunk, the lower 
arches are divided into ribs, and supporting transverse processes (par- 
apophyses). In the tail of the Selachii and Ganoidei they are continu- 
ously connected with the centrum, and run out into spinous processes, 
just like the upper arches.” (Gegenbaur, Elem. Comp. Anat., p 430.) 
Again, among fishes, generally the vertebrae of the tail develop infe- 
rior arches through which the caudal vessels pass. The segments of 
the column beyond these support ribs which arch over the viscera, but 
never meet with any sternum mesially, on the ventral parietes. The 
fins have a skeleton of osseous rays which are supported upon the iu- 
terhaeinal spines. 
So well known are they that it is not my intention in the present 
connection to enter upon the study of the scales of Amia. It is suf- 
ficient to say that they are of the cycloid type of structure and consti- 
tute the exoskeleton of this fish, being arranged much as we find them 
in the typical Teleosteans. 
Anatomists have long understood the morphology of the skeletal 
parts of the tails of fishes. Professor Huxley tersely presents the con- 
ditions for us in these words, when he says that “In all Teleostean 
fishes the extremity of the spinal column bends up, and a far greater 
number of the caudal fin-rays lie below than above it. These fishes 
are, therefore, strictly speaking, heterocercal. Nevertheless, in the 
great majority of them (as has been already mentioned, page 19), the tail 
seems, upon a superficial view, to be symmetrical, the spinal column 
appearing to terminate in the center of a wedge-shaped hypural bone, 
to the free edges of which the caudal fin-rays are attached, so as to 
form an upper and a lower lobe, which are equal, or subequal. This 
characteristically Teleostean structure of the tail-fin has been termed 
homocercal—a name which may be retained, though it originated in a 
misconception of the relation of this structure to the heterocercal con- 
dition.” 
“In no Teleostean fish is the bent-up termination of the notochord 
replaced by vertebrae. Sometimes, as in the salmon, it becomes en- 
sheathed in cartilage, and persists throughout life. But, more usually, 
its sheath becomes calcified, and the urostyle thus formed coalesces with 
the dorsal edge of the npper part of the wedge-shaped hypural bone, 
formed by the anchylosis of a series of ossicles, which are developed in 
connection with the ventral face of the sheath of the notochord.” (Anat. 
of Vert. Animals, page 131.) 
There are ninety vertebrae in the spinal column of Amia calva ; they 
are of the amphiccekms type, and devoid of zygapophysial processes 
(Fig. 14). The centra of these vertebrae are thoroughly ossified, but their 85 
THE OSTEOLOGY OF AMIA CALYA. 
neural aud haemal arches remain free throughout life, articulating with 
them upon certain facets that are overlaid by their cartilage. 
I fail to find a pair of ribs attached to the first free vertebra or 
what now corresponds to the u atlas.” Its neural arch has an inde* 
pendent spine, articulating with it, and directed backwards. A simi- 
lar spine, only longer, is found in a like position on the neural arch of 
the second and third vertebrae. Three or four others follow in sequence 
behind these, but they have no apparent connection with the neural 
arch of the vertebrae. The second vertebra supports a delicate pair of 
ribs, which articulate directly with the sides of its centrum. In the third 
segment a small pair of parapophyses have made their appearance, and 
the ribs of this vertebra articulate with their outer extremities. These 
parapophyses are characteristic of the vertebrae to the thirty-seventh 
inclusive. They are always directed downwards and outwards; are 
longest in mid series, but as they proceed backwards are situated lower 
down on the centrum of the vertebra. The ribs are long and slender 
and become more so as we proceed towards the tail; in every case they 
articulate with the extremity of the parapophyses. 
The extremity of the neural spine of the sixth vertebra in Ami a is 
bifurcated, and this feature is present for about two-thirds the way 
down the column; these spines being directed upward and backward, 
with the ones over the middle of the abdominal cavity more decidedly 
backwards, though the rear spines are the most deeply bifurcated. 
Twenty of the ultimate ones are simple in their structure. Not very 
well marked parapophyses are found upon the thirty-eighth vertebra, 
and this segment is without a pair of ribs. The neural arches inclose 
quite a capacious neural canal, and their bases articulate between each 
consecutive pair of vertebrae, these latter having a form to accommo- 
date themselves to this unique condition (Fig. 26). No neural arch 
is found upon the forty-fifth vertebra, and from that onwards they only 
occur upon the alternate segments. In the thirty-ninth vertebra, what 
would at first appear to be the parapophyses in the anterior part of the 
column, are here much larger, freely articulated, and inclose a canal by 
the union of their extremities beneath, in the medium plane. These 
also skip the same vertebra as the neural arches do above them on the 
column; fourteen of them also support a free spine from their mid points 
below. After this they are united and pass round the bent-up verte- 
bral column, becoming broader and gradually shorter, where they sup- 
port the caudal fin rays (Fig. 25). The last six or seven of these 
haemal spines appear to be anchylosed with the vertebrae. 
I count in my specimen before me, fifty-three bony rays in the long 
dorsal fin; these branch above, and the ultimate ones branch a second 
time. These rays are supported by an equal number of inter spinous 
hones, through the intervention of little ossicles that pass obliquely 
from one to the other (Fig. 25). All this part has been quite correctly 
figured by Franque, but this author overlooked a series of delicate little REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
bones that continue tbe interspinous bones of the dorsal fin as far as 
the caudal fin. These are five in number and are seen at jf in Fig. 
25. The rays of the dorsal and anal fin split longitudinally, as I de- 
scribed them for the pectoral and ventral fins. The anal fin possesses 
twelve rays in its membrane, and likewise twelve interspinous bones 
support it, of which the majority in the mid-series have intermediate 
ossicles as in the dorsal fin. These little bones are each shaped like a 
dice-box, and not as Franque has represented them in his drawing. 
My representation of the skeleton of the tail of Amia I have taken 
so much pains with to secure its accuracy that I believe any verbal 
description of the parts hardly necessary. (Fig. 25.) More time than 
usual was devoted to this figure, because the illustrations of this part 
of Amia’s anatomy that it has been my pleasure to examine are far 
from being correct; they are carelessly drawn or simply diagrammatic 
in character (Kolliker’s). 
There are twenty-five rays in the caudal fin of this Ganoid. Of these, 
the two superior ones are very delicately fashioned, the next two are 
long and slender, while the stoutest ones are found in the middle, from 
which series they gradually become smaller again as we proceed down- 
wards. In the prepared specimen all of these rays are found to be 
split longitudinally in the vertical plane, and those chosen from near 
the middle of the member are found to be branched to the third or 
fourth division. They are also marked at irregular intervals by raised 
and transverse divisions. The splitting spoken of allows these rays to 
seize by their anterior ends the hypural bones coming from the verte- 
bral column, which they do in the manner shown in the figure. In this, 
the best living example of a masked lieterocercal tail, the notochord, 
being insheathed only in cartilage, has, of course, disappeared in the 
figure. It is in Polypterus that we find nearly the type of what has 
been termed the “ dipliycereal” tail, in which the notochord is scarcely 
bent up at all. Our example of Micropterus shows in a marked degree 
the remaining style of the skeletal parts of the tail in osseous fishes. 
This is well known to us under the term of the liomocercal type, and in 
this fish shows a very completely ossified urostyle, directed upwards 
and backwards at an angle of about 45°, with a markedly straight ver- 
tebral column. The hypural plates are also very broad and perfect in 
this bass, and the fin rays, very similar in construction with those de- 
scribed for Amia, are attached to them in the same manner. As in so 
many osseous fishes, Micropterus has on either side, close to and be- 
tween the column on the third hypural plate, a sharp, upturned pro- 
cess. This I believe is intended to afford additional surface and lever- 
age for the origin of the muscle that controls the movements of the 
tail. 
In speaking of tliis part of Alma’s anatomy Wilder says 68 that “ the 
68 Wilder, Burt G., Ou the tail of Amia. Proc. Amer. Association for the Adv. of 
Science, 1876, pages 264-266. THE OSTEOLOGY OF AMIA CALVA. 
tail of Amia has been figured and described by Franque, Kolliker, and 
Huxley.”69 
Kolliker’s paper is known to me only through the quotations by 
Dumeril. Franque represents only the osseous portions of the skeleton. 
Huxley gives both form and structure, but not, as it seems to me, quite 
accurately. [Neither of these authors mentions the young Amici, or inti- 
mates that the form or structure of the tail may vary with age. In 
discussing the external form this author further remarks that “ Dumeril 
says that the tail of Amia, as to its external appearance, differs in no 
way from that of the ordinary osseous fishes. Its heterocercy, however 
decided, is well manifested only by the skeleton.” Huxley does not 
allude to the form, but his figure does not very distinctly indicate any 
difference between the tail of Amia and that, for instance, of some Silu- 
roids, where the whole is rounded, and the greatest length is midway 
between the dorsal and ventral borders.” 
And, continuing, in the same article lie sums up the results of his val- 
uable observations, and says: “I have examined many examples of 
Amia, young and adult, and all manifested the following features: 
“1. The greatest length of the tail is considerably above the middle 
of its height. 
u 2. The change from the nearly horizontal dorsal and ventral borders 
to the curved posterior border occurs farther forward upon the ventral 
side. These features render the ventral slope both longer and more 
gradual than the dorsal. 
“ 3. When the tail is fully expanded, as while the fish is swimming, 
the dorsal and ventral slopes meet, so as to form a gentle curve, and 
not an obtuse point, as in Huxley’s figure. This is well shown in (Fig. 3 
representing) the tail of a young example in the condition assumed at 
death. 
u The tail of Lepidosteus presents the same general features, with some 
specific variation. Hence, with both these ganoid genera the external 
form of the tail is decidedly, though not very obviously, unequal.” 
My interest was first awakened in tlie structure of Amici more than 
ten years ago, at which time I was permitted to attend Dr. Wilder’s 
lectures at Cornell University, where dissections upon Amici calva al- 
ways held a prominent place. In those days, however, if I remember 
correctly, Dr. Wilder had made but few, if any, dissections of the 
young of Amici, so it affords me additional pleasure and a peculiar 
satisfaction to further quote from his paper in the Proceedings his 
remarks upon the structure of this part of the mudfish’s anatomy, 
supplemented, as it now has been, by studies in that direction. Of it 
he says that u the terminal caudal vertebrae form an upward curve, 
69 I have, for obvious reasons, referred to elsewhere in this article, omitted Dr. 
Wilder’s number references to his bibliographical table at the end of the above paper 
in the Proceedings; as well as the references in his text to the figures of his in- 
structive plate. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
as shown by Franque. Huxley’s figure and description show that the 
notochord, enveloped by cartilage, extends upward toward the dorsal 
border of the tail. In all the adults examined by me the termination of 
this compound rod is considerably nearer the dorsal border than is in- 
dicated by Huxley’s figure, and presents a rather broad and but slightly 
rounded tip, with a central depression corresponding to the neural or 
spinal canal. Here ends the distinct cartilage. Posterior to it, and be- 
tween the two laminae of the twenty-first or twenty-second fin-ray (count- 
ing from below), is a tract of gelatinous matter, which Kolliker, as quoted 
by Dumeril, seems to have regarded as the prolongation of the noto- 
chord. I have been unable to detect any difference between this and 
the tracts of gelatinous matter between the laminae of the other caudal 
fin-rays. 
“ But that it may fairly he regarded as the prolongation of the noto- 
chord, degenerated, and not enveloped by a cartilaginous sheath, is 
rendered at least probable by the following considerations: 
“ 1. The condition of things in the adult Lepidosteus, as described and 
figured by Kolliker and myself; the notochord with its cartilaginous 
sheath forming a slender tapering rod, extending between the halves of 
fin-rays to the junction of the middle and hinder thirds of the tail. 
“ 2. The existence of an undulation of the dorsal border of the tail of 
Amici corresponding with the termination of the supposed notochord. 
“3. The greater distinctness of this undulation in young individuals.” 
This interesting paper concludes with remarks upon “ transforma- 
tion” and “variations in the shape of the tail.” 
Counting the one from which the urostyle springs, Micropterus reck- 
ons thirty-two vertelme in its spinal column, fifteen of which are ab- 
dominal. These latter all support each a pair of ribs, which in their 
turn, all save the last four pair, have epipleural appendages. The atlan- 
tal pair articulate Avith the vertebra at the very base of the neural arch, 
but as Ave proceed backwards they gradually recede from this posi- 
tion so as to finally spring from beneath the transverse processes on 
the under side of the vertebra. This condition is characteristic of a 
great many of the osseous fishes. The neural and hemal arches of this 
form are completely anchylosed with the vertebral elements, and in the 
best developed segments, both superior and inferior, post- and prezyga- 
pophyses are present. 
The arrangement of the osseous fin-rays and interspinous bones in 
Micropterus differs somewhat, to be sure, from the arrangement of these 
parts in Amia, but not at all from what we have known to exist so long 
in Teleostean fishes, as in Pe\'ca for example. 
Thus we see it is, that although the Ganoid Amia calva has in its 
skeleton many of the characters in common Avith the highly specialized 
forms as the Teleosteans, it is, on the other hand, still stamped Avith 
characters, more particularly in its vertebral column, of a veritable 
paleoichthyic type. THE OSTEOLOGY OF AMIA CALVA. 
LIST OF THE PRINCIPAL WORKS, COMPRISING OTHERS THAN THOSE 
CITED IN THE FOOT-NOTES, THAT HAVE BEEN EITHER REFERRED 
TO OR EXAMINED DURING THE PREPARATION OF THIS MEMOIR. 
1. Agassiz, L. Young garpikes from Lake Ontario. Proc. Boston Soc. of Nat. 
Hist. 1856. VI, 48. 
2. Agassiz, L. Lake Superior; its Physical Character, Vegetation, and Animals. 
pp. 428. 8 pis. Boston. 1850. 
3. Agassiz, L. Observations surles metamorphoses des poissons. Ann. des sci. nat. 
1865. Ill, 55-58. 
4. Agassiz, L. Observations sur les poissons fossiles. 1833-45. 4 vols. 4to. 
5. Agassiz, L. Notice of a collection of fishes from the southern bend of the Ten- 
nessee River. Am. Jour, of Sci. N. s. No. 21. 353-365. 
6. Agassiz, L. A Journey in Brazil. 8vo. Ills. 1868. 
7. Agassiz, L. An essay on classification. Lond. 1850. 
8. Agassiz, L. The classification of the Siluroid fishes. Proc. Boston Soc. Nat. 
Hist. 1868. p. 354. 
9. Agassiz, L. Contributions to the natural history of the United States. 4to. 
4 vols. 
10. Balfour, F. M. Development of the urogenital organs of vertebrates. Journal 
of Anat. and Phys. Vol. X. Pt. 1. 1875. 
11. Bloch, M. E. Systema Ichthyologiae. 1801. 
12. Boake. On the fishes inhabiting the Ceylon marshes. Jour, of the Ceylon branch 
of the Royal Asiatic Soc. 1865. 
13. Bridge, T. W. The cranial osteology of Amia calva. Journ. of Anatomy and 
Physiology, Vol. XI, 1877, pages 605-622. 
14. Busch, W. De Selachiorum et Ganoideorum encephalo. 4to. 1848. 
15. Cope, E. D. Observations on the systematic relations of fishes. Proc. Am. 
Asso. Adv. Sci. 1871. 
16. Cuvier, G., and Valenciennes., A. Histoire naturelle des poissons. Vol. XIX. 
1846. 
17. Cuvier, G, Le Regne animal. 1829. 
18. Day, F. Observations on some of the fresh-water fishes of India. Proc. Zool. 
Soc. of Lond. 1868. 274-288. 
19. Dobson, G. E. Notes on the respiration of some species of Indian fresh-water 
fishes. Proc. Zool. Soc. Lond. 1874. 312-321. 
20. Dumeril, Aug. Histoire naturelle despoissons ou ichthyologie gdndrale. Tome 
I. Elasmobranches (sharks, skates, and chimerse), pp. 720; 14 plates. 1865. 
Tome II. (Gano'ides, Dipn6s, Lophobranches), pp. 625; 12 plates. 1870. 
Paris. 8vo. 
21. Foster, M., and Balfour, F. M. The elements of embryology. 16mo. Lond. 
1874. 
22. Franque, Henricus. Amite calvse anatomium descripsit tabulaque illustravit. 
folio, pp. 12, 1 plate. Berlin. 1847. 
23. Gegenbaur, C. Ueber die Kopfnerven von Uexanclms. Jenaische Zeitschrift. 
VI. Taf. XIII. 1871. 
24. Gill, T. N. Arrangement of the Families of Fishes. Smith. Inst. Miss. Coll. 1872. 
25. Goodsir, John. Anatomical memoirs. 8vo. 2 vols. pp. 993. Edin. 1868. 
26. Gottsche, C. M. Vergl. Anat. des Gehims der Gratenfische. Arch, fur Anat. 
1835, 244-294 ; 483-486. Taf. IV and VI. 
27. Gunther, A. Ceralodus and its place in the system, pp. 5. 2 figs. Ann. and 
Mag. of Nat. Hist. 1871. VII, 222-227. 
28. Gunther, A. Description of Ceratodus, a genus of Ganoid fishes recently discov- 
ered in the rivers of Queensland, Australia. Phil. Trans. Royal Soc. Lond. 
1872. pi. 30-42. REPOET OF COMMISSIONER OF FISH AND FISHERIES. 
29. Gunther, A. Article Ichthyology. Encycl. Brit. Vol. XII. 9th ed. 1861. 
30. Hollard, H. Recherches sur la structure de l’encdphale des poissons et sur la 
signification homologique de ses difi£rentes parties. Robin’s Jour, de l’anat. 
1866. 286-335. pi. v-viii. 
31. Humphrey, G. M. On the homological relations to one another of the mesial 
and lateral fins in osseous fishes. Jour. Anat. & Phys. November, 1870. 
59-66. 
32. Huxley, T. H. Preliminary essay upon the systematic arrangement of the fishes 
of the Devonian epoch. Mem. Geo. Surv. of the U. King. Decade X. 1861. 
33. Huxley, T. H. Manual of the comparative anatomy of the vertebrated animals. 
N. Y. 1872. 
34. Huxley, T. H. Observations on the development of the tail in Teleostean fishes. 
Quart. Jour. Micro. Sci. VII. 33-44. Plate III. 1859. 
35. Huxley, T. H. On Ceratodus Forsteri. Proc. Zool. Soc. Lond. January 4, 
1876. 
36. Jordan, D. S., and Gilbert, C. H. Synopsis of the fishes of North America. 
Bull. U. S. Nat. Mus., No. 16. 1882. 
37. Jordan, D. S. Manual of the vertebrates of the Northern United States, exclu- 
sive of marine species, pp. 342. 12mo. Chicago. 1876. 
38. Kolliker. Ueber das Ende wirbelsatile Ganoiden und einigen Teleostien. 1860. 
39. Lacep&de. Histoire des poissons. 
40. Langerhaus, Paul. Zur Anatomie des Amphioxus lanceolatw. Archiv fur Kros- 
kopische Anat. Band XII. Zweites Heft. 1875. Taf. XII-XV. 
41. Le Conte, Joseph. Elements of geology. New York. 1883. 
42 * Linnaeus, Carl von. Systema naturae. 12th ed. 1766. 
43. Liitken, C. On the limits and classification of the Ganoids. Trans. Ann. & 
Mag. of Nat. Hist. 1871. 329-339. 
44. Mayer, P. J. C. Ueber den Bau der Gehirns Fische inBezieliung auf eine darauf 
gegrundete Eintheilung dieser Thierklasse. Mit sieben Steintafeln. pp. 
40. Novorum Actorum * * * Naturae Curiosorum. Tom. Vicesimus 
Secundus. 1864. 
45. Miklucho-Maclay. Beitrag zur vergleichenden Anatomie des Gehirns. pp. 19. 
3 figs. Jenaischen Zeitschrift fur Medicin und Naturwissenschaft. 1868. 
46. Miklucho-Maclay. Beitrage zur vergl. Neurologie der Wirbelthiere. Leip- 
zig. 1870. 
47. Milne-Edwards, A. Lemons sur la physiologie et l’anatomie compare de 
l’homme et des animaux. Tome deuxibme. 1857. 
48. Mivart, St. George. Lessons in elementary anatomy. Lond. 1877. 
49. Moreau, A. Recherches expdrimentales sur les fonctions de la vessie natatoire. 
Ann. des sciences nat. Tome IV. 1876. pp. 85. 2 plates. 
50. Muller, Johannes. Vergleichende Neurologie der Myxinoiden. Abh. der konigl. 
Akad. zu Berlin. 1838. 
51. Muller, Johannes. Ueber den Bau und die Grenzen der Ganoiden und liber das 
natiirliche System der Fische. Abhandiung der koniglichen Akademie der 
Wissenschaften zu Berlin. 1844. Quarto. 117-216 ; 16 plates. 
52. Muller, Johannes. ‘Berickt fiber die Fortschritte der vergleichenden Anatomie 
der Wirbelthiere im Jahre 1842. Archiv ffir Anat. 1843. ccxxxviii-cclxi. 
53. Muller, Johannes. Ueber den eigenthumliclen Bau des Gekororganes bei den 
Cyclostomen, mit Bemerkungen fiber die ungleiche Ausbildung der Sinnes- 
organe bei den Myxinoiden. pp 34. Taf. 1-3. Abhandlungen der konig- 
lichen Akademie der Wissenschaften zu Berlin. 1837. 
54. Muller, Johannes. M6moire sur les Ganoides et sur la classification naturelle 
des poissons. 1845. Ann. des sciences nat. 3me s6rie, Tom. IV. 1845. 5-53. 
55. Newberry, J. S. Description of fossil fishes of Ohio. pp. 110. 17 plates. 
Geol. Surv. of Ohio. Vol. 1. 1873. 91 
THE - OSTEOLOGY OF AMIA CALYA. 
56. Ord, Wm. M. Notes on comparative anatomy. Lond. 1871. 
57. Owen, R. Description of Lepidosiren annectens. Linn. Trans, xviii. 5 plates. 
58. Owen, R. Comparative anatomy and physiology of vertebrates. 3 vols. 8vo. 
Lond. 1861-68. 
59. Parker, W. K. On the development of the salmon’s skull. Trans. Royal Soc. 
Yol. 163. 
60. Parker, W. K., and Bettany, G. T. The morphology of the skull. Lond. 1877. 
61. Poey, P. Observations on different points in the natural history of Cuba. Ann. 
of the Lyceum of Nat. Hist. N. Y. 1858. VI, 136. 
62. Shufeldt, R. W. Osteology of the large-mouthed black bass (Micropterus sal- 
moides). Science, Yol. Ill, No. 65. May 2, 1884. Cambridge. 
63. Stannius, H. Ueher den Bau des Gehirns des Stors. Archiv fiir Anatomie. 
' 1843. 36-44. Taf. III-IV. 
64. Stannius, H. Handbuch der Zootomie. 2. Theil. 2d ed. 1854. 
65. Tiedemann, F. The anatomy of the foetal brain; with a comparative exposition 
of its structure in animals. (Eng. Trans.) 14 pis. Edinburgh. 1826. 
66. Valentin. Ueber das centrale Nervensystem and die Nebenherzen der Cliimcera 
monstrosa. Arch, fiir Anat. 1845. 25-45. Taf II. 
67. Vogt, C. Quelques observations sur les caracthres qui servent a la classification 
des poissons ganoides. Ann. des Sci. nat. 3me s6rie. Tom. XIV. 1845. 
68. Vulpian, A. Logons sur la physiologie gdndrale et comparative dn systeme 
nerveux. 1861. 8vo. pp. 20. 
69. Wilder, B. G. Notes on the N. A. Ganoids. I. On the respiratory actions of 
Amia and Lepidosteus. Proc. Am. Asso. Adv. Sci. 1875. 151-153. 
70. Wilder, B. G. On the serrated appendages of the throat of Amia. Proc. Am. 
Asso. Adv. Sci. 1876. 259-263. 
71. Wilder, B. G. On the tail of Amia. Proc. Am. Asso. Adv. Sci. 1876. 264-266. 
72. Wilder, B. G. Notes on the development and homologies of the anterior brain- 
mass with sharks and skates. Am. Jour. Sci. August, 1876. 105. 1 fig. 
73. Wyman, Jeffries. Anatomy of the nervous system of Bana pipiens. Smith. 
Contri. to Knowledge. Y, Art. 4. 1855. 4to. pp. 51, 2 pis. 
74. Wyman, Jeffries. Observations on the development of Baia batis. Memoirs of 
Amer. Acad, of Arts and Sci. 1874. 4to. 1 pi. EXPLANATION OF THE REFERENCE LETTERS USED IN 
THE PLATES. 
[Note.—In many instances in Dr. Sagemehl’s article the letters in his text do not 
agree with the reference letters of the figures in his plate; then, again, Franque used 
a different system of letters, as did the writer. This gave much trouble ; but it is 
hoped that in the explanation of these letters, here given, the references will all be 
made clear, both for the text and the figures.—R. W. S.] 
a. Admaxillary; frontal (Fig. 7, Plate II); also one of the ossifications of Meckel’s 
cartilage (see Plate V, Figs. 17 and 18), and a a ligament between nasal and 
frontal. [Franque.] 
ag. Angular. [Bridge.] (See Plate V, Figs. 17 and 18.) Also Ang. (Plate III and 
others.) 
An. Preorbital (Plate IY, Fig. 16) ; antorbital. 
an. Angular (Plate VII). 
Art. Articular (P5, os condyloideum of Franque, Plate X). 
As. Alisphenoid. 
Ast. Actinosts. 
/?. Ossa in cutem immissa (Franque), supratemporal of the author 
b. Parietal of Frauque (Fig. 7). 
b. One of the ossifications of Meckel’s cartilage (Plate Y, Fig. 17). 
b. a. Branchial arches. 
B. 0. Basioccipital. 
Brs. B. Branchiostegal rays. 
B. 8. Basisphenoid. 
Bs. b. Basibranchials. 
c. One of the ossifications of Meckel’s cartilage in Plate V. 
c. Os mastoideum (Franque), the squamosal of the other figures; Sq. 
ca. Carotid foramen. 
cb. Vascular canal of the occiput (in basioccipital). 
ce. External semicircular canal. 
C. hy. Cerato-hyal. 
cp. Posterior semicircular canal. 
cr. Coronary cartilage (Bridge), Plate V, Fig. 17. 
Cs. Anterior semicircular canal. 
c. v. Neural arch of first vertebra in Albtda and the co-ossified first vertebra in Mega- 
lops. 
D. Dentary. 
d. One of the ossifications in Meckel’s cartilage. (Bridge.) Plate V. 
d. Nasal. (Franque.) PI. II, Fig. 7. 
d'. Os alare (Franque); the author’s antiorbital, while Franque’s antorbital h I have 
the lacrymal. 
S'. Posterior nasal aperture. (Franque.) 
e. Ethmoid of Franque. (PI. II, Fig. 7.) 
JEcpl. Ectopterygoid. 
E. hy. Epihyal. 
92 THE OSTEOLOGY OF AMIA CALVA. 
Enpt. Entopterygoid. 
E. 0. Exoccipital. (See also Ex., Fig. 1.) 
ep. Epiphysial crest. 
Ep. 0. Epiotic. 
Esc. Extrascapula. (Sagemehl.) Fig. 1. 
Eth. Ethmoid. • 
* 
Ex. Exoccipital. (Sagemehl.) 
F. Frou.tal. 
/. Superior maxilla. (Franque.) PI. X, Fig. 26. 
fa. Foramen for exit of facial nerve. 
/7t. Hypophysial foramen. 
g. Intermaxillary. (Frauque.) 
G. hy. Glossohyal. 
gph. Foramen for glossopharyngeal nerve. 
G. Gular plate. 
h. Antorbital. (Franque.) PI. II, Fig. 7. 
II. hy. Hypohyal. 
H. M. Hyomandibular. 
hm. Articular facet for hyomandibular. 
Hyo. c. Hypocoracoid. 
Hyp. c. Hypercoracoid. 
i. Infraorbital bones. (Franque.) (PI. X, Fig. 26.) 
ih. Interhyal. 
I. Op. Interoperculum. 
Jc. Iutercalare (opisthotic). Dr. Sagemehl evidently meant Ic. to appear on his 
figures, and this must be a mistake of his engraver. 
jf. Continuation of interspinal bones. (Not previously described.) 
jn. Membranous tract extending between frontals and nasals. 
k. Postorbital. (Franque.) PI. II, Fig. 7. 
k, k', k". Designate, with a small unnumbered piece above them, a disconnected 
chain of bones, that are sometimes found in Amia, between the postorbitals and 
preoperculum. (Plate IY, Fig. 16.) 
La. Lacrymal. 
m. c. Meckel’s cartilage in Plate III, Fig. 15. 
mk. Meckel’s cartilage. (Bridge.) Plate Y, Fig. 17. 
M. Pt. Metapterygoid. 
mt. mk. Mento-Meckelian bone. 
Mx. Maxillary. 
n. Suprascapula. (Franque.) Plate II, Fig. 7. 
Na. Nasal. 
Ea". A semicartilaginous piece of bone found in Albula vulpes. Figs. 29,30. 
Ob. Basioccipital. (Sagemehl.) 
Oc. I, Oc. II. First and second occipital arches of Amia. (Sagemehl.) 
oc. I, oc. II, and oc. III. Foramina of exit of the first to the third occipital nerves in 
Amia. (Sagemehl.) 
oc. r. Occipital ribs in Micropterm. (Shufeldt.) 
01. Occipitale laterale. (Sagemehl.) 
ol. Opening for nasal nerves. 
Op. Operculum. 
op. Optic foramen. 
Os. Orbitosphenoid. 
P. Inframaxilla. (Franque.) 
PI. Dentary. 
P3. Coronoid. 
P5. Os condyloideum. REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
94 
Pa. Parietal. 
Pe. Petrosal. (Sagemehl.) 
Pf. Pectoral fin. 
pi. Dr. Sagemehl gives this in his figures, but not in his list. 
Pmx. Premaxillary. 
P. Op. Preoperculum. * 
01' } Postorbitals. 
P. or1. ) 
Prf. Prefrontal. 
Pr. 0. Prootic. 
Pr. S. Parasphenoicl. 
P. Sc. or Ps. Proscapula (Plate XIV, Fig. 35). Ps. Parasphenoid of Sagemehl. 
Psf. Postfrontal. 
Psto. T. Posterotemporal. 
Pst. T. Posttemporal. 
Pi. 0. Pterotic. 
Pv. Pelvis. 
q. Operculum. (Franque.) 
ql. Interoperculum. (Franque.) 
q*. Suboperculum. (Franque.) 
q\ Preoperculum. (Franque.) 
Qu. Quadrate. 
ro. Facet for articulation with operculum. 
8. Os pterygoideum externum seu transversum. (Franque.) 
Sag. or S. Ang. Surangular. 
Sb. o. and Sb. o1. Suborbitals. 
Sc. Suprascapula. 
S. eth. Supraethmoid. 
si. Supralinear. 
Smx or Sm. Intermaxilla, septomaxillary. 
S. O. Supraoccipital. 
S. Op. Suboperculum. 
Sq. Squamosal. 
S. tp. Supratemporal of Bridge and the author; extrascapula of Sagemehl. 
Sym. Symplectic. 
T. Teleotemporal. 
T1. Lower teleotemporal. 
Tn. Teeth. 
tg. Temporal fossa. 
tr. Foramen for the first branch of trigeminal nerve. Tr. For the second and third 
branches of the same. 
v. Foramen for exit of vagus. 
V. f. Ventral fin. 
vg. Vagus foramen. 
Vo. Vomer. 
x. Two small pieces of cartilage posterior part of cranium of Amia. (Sagemehl.) 
Yn. Coracoid of Amia (in cartilage). 
z. One of the ossifications of Meckel’s cartilage; the one marked a in Plate V, Figs. 
17 and 18. PLATE I. 
Fig. 1. Cranium of Amia calva from above; life size. The dark piece projecting at 
the lower right-hand angle is the continuation of Sc. The little piece at 
the anterior end of the frontal suture is in cartilage, as is ol, and the trian- 
gular wedge at the inner end of Esc. Sagemehl’s original plates have all 
the cartilage tracts in color, a pale blue. This could not be carried out in 
the present connection. The lightly stippled and unlettered parts, gener- 
ally, are in these figures, however, the cartilaginous tracts. 
Fig. 2. The same specimen, cranium seen from below. 
Fig. 3. The same specimen, the parasphenoid (Ps.) and the vomers (Vo) having been 
removed. (These three figures copied from Sagemehl’s plates by Mr. H. L. 
Todd.) 
96 .Report U. S. F. C. 1883.—Shufeldt. Anna calva. 
PLATE L 
Fig 3. 
F'ffM 
Fiy/. PLATE II. 
Fig. 4. The skull of Amia calva vertically bisected through the median line; same 
specimen ; life size. (After Sagemehl.) 
Fig. 5. The same; lateral view of the cranium before bisection. (After Sagemehl.) 
Fig. 6. Primoidal cranium of Amia calva; same specimen as before, viewed from 
above after the removal of all the “ cover bones; ” life size. The cartilage 
tracts here are between the premaxillaries (Pmx); at ol; all the central 
portion and the lateral fossae, ta. (After Sagemehl.) 
Fig. 7. Superior view of the skull of Amia calva, with all the “ cover bones” in siiu. 
Life size. (After Franque.) The figures in this plate copied by Mr. H. L. 
Todd from the author’s figures as given. 
98 Report XJ. S. F. C. 1883.—Slnifeklt. Aniia calva. 
PLATE IL 
Figr.f: 
FcyS 
Fig/- 
Fig 6. PLATE III. 
Figs. 8 and 9. Transverse sections through the cranium of Amia calva in the region 
of the nasal pits. Fig. 8 the anterior section, and they follow in sequence 
through Fig. 12. The sections are diagrammatic; with the cartilaginous 
parts stippled. (After Sagemehl.) Copied by Mr. Ii. L. Todd. 
Figs. 10, 11, and 12. Similar sections through the region of the optic foramen, the 
facial foramen, and the labyrinth region just anterior to the foramen for the 
glossopharyngeal, respectively. (After Sagemehl.) Copied by Mr. Todd. 
Fig. 13. Posterior view of the cranium of the same specimen of Amia calva. Life size. 
(After Sagemehl.) Copied by Mr. Todd. 
Fig. 14. Three vertebrae of Amia calva, magnified about three times, showing the 
method of articulation of the neural spines and the facets for the ribs. 
(After Frauque.) Copied by Mr. Todd. 
Fig. 15. Left lateral view of mandible of a Teleostean fish (Alicropterus salmoides). 
Life size. Drawn by the author from his own dissections. The various 
bones pulled apart to show their entire shape. 
100 Ueport U. S. F. C. 1883.—Shufeldt. Aiuia calva. 
PLATE III. 
J* ig. 99 
r.y io. 
F8. 
fX9 42. 
FiaJ/. 
Fir/13. 
Tig .14-. 
i5. PLATE IV. 
Fig. 16. Right lateral view of the skull of Amia calva, showing the arrangement of 
the Ganoid plates. Life size from nature, by the author. This specimen 
was collected by me near New Orleans, La., in 1883. 
102 Report U. S. F. C. 1883.—Shufeldt. A mi a oalva. 
PLATE IV. 
Fuj.16'. PLATE V. 
Fig. 17. Inner aspect of the right half of mandible of Amia calva, the 6plenial ele- 
ment removed. (By the author, after Bridge, somewhat enlarged.) 
Fig. 18. The same view from a specimen in my own possession ; the splenial element 
in situ, together with the bones connecting it with the symphvsis. En- 
larged. (From nature, by the author.) 
104 .Report U. S. F. 0.1883.—Shufeldt. Amia calva. 
PLATE V 
iW7 
Ftp. Id. PLATE YI. 
Fig. 19. The palatopterygoidean arcade of Amia calva, together with other associated 
houes and the hyoidean arch, to the outer side of which articulate the 
• twelve branchiostegal rays, Brs. R. The dotted portions about, the hypo- 
hyal, metapterygoid and epihyal represent cartilage, but all other cartila- 
ginous and membranous portions have been carefully removed. This figure 
well shows the relation of the hyoidean arch to the other bones represented, 
as it does the position occupied by the semi-anchylosed preoperculum. 
Life size from nature, by the author. 
106 Report IJ. S. F. C. 1883.—Shufeldt. Amia calva. 
PLATE VI. 
i'n 
4" PLATE VII. 
Fig. 20. Inferior aspect of the mandible of Amia calva, showing the normal position 
of the gnlar plate, G. pi. Life size from nature, by the author. 
Fig. 21. A longitudinal, vertical, median section of the cranium of a perch (Perea 
americana), inside view showing the relations of the various bones, the 
position of the otolith, the eye-muscle canal, and the bones that enter into 
the ear capsule. Adult. Slightly enlarged from nature, by the author, 
from his own dissections. 
108 Report U. S. F C 1883.—Shufelilt. Amia calva. 
PLATE VII. 
Fig-20. 
Fig. 21. PLATE VIII. 
Fig. 22. The left outer aspect of the upper jaw of a teleostean fish {Micropterus), 
together with the hones associated with it. These latter are slightly dis- 
lodged from their normal positions, the better to show their relations. Life 
size from nature, by the author, from his own dissections. 
Fig. 23. Inner aspect of left half of shoulder girdle and pectoral limb of Micropterus 
salmoides. 
Fig. 24. Same view of like parts in Amia calva. Both figures reduced one-fourth. 
From nature, by the author. 
110 Keport IT. S. F. C. 1883.—Shufeldt. Arnia calva. 
PLATE VIII. 
1’iq.ZZ. 
Fu,.Z3. 
FyZ-f. PLATE IX. 
Fig. 25. The skeleton of the caudal extremity of Aviia. The five small rods of bone, 
referred to by the letters jf, are the continuation of the internetiral spines. 
These have not been previously described, and were overlooked by Franque, 
consequently do not appear in his figure. Taken in connection with the 
free spines found over the anterior vertebrae of the column, these bones 
rather lead me to believe that in the early ancestors of Amia the fin was 
continuous, from base of cranium to include the tail. Life size from na- 
ture, by the author. 
112 Report U. S. F. 0.1883.—Shufeldt. Araia calva. 
PLATE IX. 
Tig.25. Fig. 26. Left lateral view of tlie skeleton of Amia calva. Copied by Mr. H. L. Todd 
from Franque’s figure and considerably reduced. 
PLATE X. 
114 Report XJ. S. F. C. 1883.—Sliufelilt. Amiacalva. 
PLATE X. 
T^.26. Fig. 27. Left lateral view of the skull of Micropferus salmoides, with the skeleton of 
other parts connected with it posteriorly. This figure is designed to show 
the relation of the bones, arranged in situ, of this part of the skeleton in a 
typical teleostean fish. Life size from nature, by the author, from his own 
dissections. 
PLATE XI. 
116 Report U. S. F. C. 1883.—Sliufeldt. Anna calva. 
PLATE XL 
Fit/. 2/. PLATE XII. 
Fig. 28. Palatoquadrate arch, nearly complete, right side, inner aspect, of Albula 
vulpes. Same specimen as shown in Fig. 29. The area of teeth are seen 
just above the letters Ecpt. Life size. Drawn by the author from a speci- 
men kindly lent him by Prof. Theodore Gill, from his private cabinet. 
Fig. 29. Right lateral views of cranium of Albula vulpes, and the greater part of the 
palatoquadrate arch. Same specimen as figured in Fig. 28. Life size 
from nature, by the author, from the specimen in Professor Gill’s cabinet. 
118 lieport U. S. I<\ C. 1883.— Shul'eldt. Amia calva. 
PLATE XII. 
FL9.Z8 
Fig. 29. PLATE XIII. 
FlO. 30. Superior view of the cranium of Albula vulpes. From the same specimen of 
which the lateral view is shown in Fig. 29 of this paper. Life size from 
nature by the author. 
Fig. 31. Inferior view of the cranium of Albula vulpes. The elliptical area of teeth 
are here seen upon the parasphenoid, Pr. S. Same specimen as in Fig. 30, 
from Professor Gill’s collection. Life size, from nature, by the author. 
Fig. 32. Inner aspect of opercular bones, hyoid, symplectic, and other elements of 
Micropterm salmoides. Left side. Designed to show the relations of these 
parts as found in a typical teleostean fish. Life size from nature; drawn 
. by the author from his own dissections. 
120 Report- U. S. F. C. 1883.—Shufeldt. Anna calva. 
PLATE XIII. 
Fif.3o. 
Fy.3i. 
JPig.3z PLATE XIV. 
Fig. 33. Posterior view of the cranium of Megalops. The first vertebra of the col- 
umn is anchylosed with the basioccipital, and is referred to by the letters 
r. v. Life size. 
Fig. 34. Right lateral view of the cranium of Megalops. Missing parts are seen from 
this aspect, as the parietals and basisphenoid. The normal position of 
this cranium would have the parasphenoid, Pr. s., in the horizontal plane, 
but it is represented this way to save space. This specimen is the same as 
seen in Fig. 33, and both were drawn by the author from a specimen kindly 
lent him by Professor Gill from his private cabinet. 
Fig. 35. Outer aspect of part of shoulder girdle, and the pectoral fin of Micropterus 
salmoide8. Life size. Drawn by the author from his own dissections. 
122 .Report U. S. F. C. 1883.— Shufeldt. Amia calva. 
PLATE XIV. 
33. 
J?ig.34-; INDEX. 
[Note.—The references are to page-figures in brackets.] 
Page. 
Acanthias 38 
nasal aperture in 37 ; 
Acanthopterygii 40 
Accessorisches stuck 78 
Acipenser 44 j 
Acipenserides 42 I 
Actinosts 78, 83 
Acusticus foramen 40 i 
Admaxillary 47, 53, 56 
Agassiz, L 2 
work cited 44, 81, 89 
Air-bt eathing vertebrates posterior nares of 39 j 
Albrecht, work cited 18 
Albula 62,63,65,66,71 
basisphenoid of 66 j 
cranium of 62, 63,118,120 
entopterygoid of 67 
foramen magnum of 65 
frontals of 62, 63 
hyomandibular of 67 j 
known species of 62 J 
nasals of 66 j 
no gular plate in 62 | 
opisthotic of 65 j 
palatine of 67 
palatoquadrate arch of 67,118 ] 
parietals of 63 
prefrontals of 62, 63 
prootic of 67 
quadrate ... 67 
rear view of the cranium of 64 I 
squamosals of 63 
3ymplectic of 67 
teeth of 63, 67 
vomer of 63 
vulpes 61,70 | 
Alestes. - - 35 
Alisphenoid 20, 22, 31, 36,50-54, 56, 61, 66, 69, 70 
circular 70 
descending, process of 53 
Alveolar process 10 
Amia 3, 24, 32, 44, 62, 67, 70, 79, 80 
alisphenoid of 21 j 
ancestors of 82 j 
anterior and posterior nares in 39 ! 
anterior nasal aperture of 5, 7 
anterior third ot the wall of orbit in.. 21 
basioccipital of .... 12 i 
basioccipital much elongated in 51 j 
brancliiostegal rays in 55 j 
calva, skeleton of 43 i 
canal beneath the cavum cranii of 34 j 
Page. 
Anna, canalis transversus of 33 
carpus of . 79 
caudal extremity of 112 
centrum of the hindmost vertebra of. 17 
commencement of the spinal cord of.. 11 
coossified vertebra of 65, 70 
coracoids 79 
“cover bones ” of the skull in 10 
cranial nerves in 42 
cranium of „ 9, :i9, 50, 96 
dissections of young of 87 
dissections upon 87 
dorsal fin of 85 
ectiipterygoid in 54 
entopterygoid of 54 
exoccipitals of 12, 40, 51 
external appearance of 44 
extrasc.ipula of 5 
first occipital nerve of 15 
first spinal nerve in 14 
foramen oi the alisphenoid in .... 22 
foramen of the lab,\ riuth in 25 
forms of bones in cranium of 22 
forty-fifth vertebra of •. 85 
fossil 82 
frontalia of 4 
frontal region of ll 
ganoid plates of 56 
gill-takers of \ 56 
gular plate of 50 
history of the skeleton of 43 
hyoideau and branchial arches of 55 
hyomandibular articulation in 41 
hyomandibular ot 54 
intermaxilla of 10 
internasal area in 53 
interoperculm of .» 47 
interorbital septum in 21 
interspiuous bones of 12 
labyrinth in 26 
labyrinth niches in 26 
lacrymal of 46 
lateral view of skull of 102 
length of tail in 87 
lower jaw of • '. 75 
mandible of ... 48,104 
mandible of, inferior aspect . 108 
melapterygoid of 54 
movement forward of metapterygoid 
in 55 
mucus canals in head of 6 
nasal bone of 39 
123 REPORT OF COMMTSfclONEK OF FISH ANT) FISHERIES. 
124 
Page. 
Amia, nasal cavity of 5 
nasal r egion of 5 
nasal region of the primoidal skull 
of .. . 23 
neural arch of first vertebra of 15 
neural spiue of sixth vertebra in 85 
non-lobate fins of 57 
number of vertebrae in .. 84 
occipital arches of 12, 13 
occipital nerves of : 14 
occipital region of 11, 40 
occiput of 17 
opercular bones of 47 
operculum of 47 
opthalmie artery in 23 
optic nerve in 23 
orbital base in 21 
obital region in 41 
orbitospheneid of 22 
ossa parietalia of 4 
os squamosum of 4 
palatine of 54 
palatopterygoidean arcade of 106 
paleoichthyic type of skeleton of .. 88 
parasphenoid of 9 
pectoral limb in 110 
pelvic bones of 82 
petrosal of 20 
plans of structure in the skull of ... 42 
position of the metapterygoid in 55 
posterior occipital arch of 14 
posterior part of orbit in 21 
' posterior view of the cranium of 100 
posterotemporal in 78 
postfrontal of 4,20 
postorbital process of 40 
postorbitals of 46 
posttemporal of 78 
prefrontal of 4 
prenasal region in 53 
primoidal cranium of 10,22,98 
progressive developmont of 10 
proscapula of 79, 80 
pterotics absent in 52 
quadrate of 54 
ramus palatinus of 20 
relation of the labyrinth to the 
cavum cranii in 25 
respiratory function in living 81 
rhinalchamber of 5 
scales of 84 
second occipital nerve of 15 
sections through the cranium of 100 
septomaxillare in 23 
serrated appendages of the throat of. 80 
shoulder girdle of 77,80 
skeleton of 114 
skull of 2,39,43,56,98 
spinal column of 84 
structure of its heart 2 
studies of the skeleton of 57 
suberanial canal of 33 
suboperculum of 47 
superior view of skull of 98 
supra-occipital absent in 42, 51 
Pago. 
Aiuia, supra-scapula of 5 
sympleotic of ...... 54 
tail of 86, 87, 88 
teeth of 48 
teleoteropor.ds of 78 
the orbits in 21 
the three occipital nerves of 15 
thirty-eighth vertebra of 85 
thirty-ni th vertebra of 85 
twenty-five rays in caudal fin of 86 
unprepared head of... . 3 
use assigned to appendages at throat 
of...... 82 
ventral fins of 82 
vertebral column of 17,83 
vertebrae of . .. . ... 100 
vomers of 9,10 
young of 87 
Amia* Calvse, Anatcmiau Descripsit Taba- 
laque Illustravit -. 43 
Amiid® 44 
Amniota atlas of the 18,19 
inner nasal opening in 37 
Amphibia 10,27,29,56 
axis of 18 
cranium of > 18 
first spinal nerves in the 18 
gill cleft of the higher 30 
inner nasal opening of 37 
larval and adult forms of 57 
occipital part of the skull of the.. 18 
occipital region in 18 
odontoid process of the 18 
skulls in . 18 
sound conducting apparatuses in 28 
specialized 56 
Anacanthini 2 
A nal fin, number of rays ir 86 
Anatomie des fische 1 
Anatomy and Physiology, Journal of 1,43 
45, 46, 52 54, 56 
Angular .. 48, 75 
Anterior occipital ai ch 14,16 
Ant orbital 5 
processes 10,21,23,41 
region 10 
Anura 28,29 
Aquaeducti vestibuli 41 
Amiidae 07 
Army Medical Museum 1 
Arrangement of the families of fishes 77 
Articular 75, 76 
Atlas 8® 
centrum of .. 59 
Atrium sinus imparis 24 
Auditory apparatus 30 
capsule 27, 52 
Baird, Professor Spencer F 
Balfour 3~ 
Balfour, F. H., work cited 38, 89 
Basi branchial elements 55 
Basibranchials '0 
Basioccipital 13, 14, 20, 24, 59, 60, 61, 04, 65, .0 
canal in 15 
condyle - • - 05 125 
THE OSTEOLOGY OF AMIA CALVA. 
T’age. 
Basioccipital, free anil independent neural 
arches upon. < 15 
Basisphenoid 56, 60, 61 
Basisphenoidea. 32 
Bass, adult 60 
black 61 
teleotemporals of 79 
Belone 39 
Berolini 1 
Black bass large-mouthed 57,73,75 
osteology of the large-mouthed. 59 
Block, M. E., work cited 89 
Boake, woi k ci ed • 89 
Bone corpuscles 7 
of Cams, displaced iliac bones 79 
Brachial 78 
Brain case in Megalops, parietes, of the.... 70 
B. auchiae accessory 82 
Branchial arches 75 
Brauchiostegal rays 80 
Bridge, T. W 1, 8, 32,45, 46, 50, 51 
Bridge, exoccipital of 50 
nomenclature of cranial elements 
used by 52 
prooiic uf 50 
Bridge, T. W, work cited, 2,3,4 
13, 2 !, 43, 47, 48, 52, 53, 54, 55, 56, 89 
Brustflosse, Basal stiiche der 78 
Buccal cavity, lames of 9 
teeth on the bones of 19 
Bulbi olfacturii 34 
Bulbus 32, 35 
aiteriosus 57,62 
olfactories ... 34,35,36 
Bulla acustica 25 
Bii:-ch, W. work cited 89 
Cambridge 59 
Canal, eye-muscle 23, 53, 60 
suberanial 32 
Canalis tiansversus 33 
Cape Cod 62 
Cardium ... 12 
Carotid arteries, openings of 53 
artery 32 
Carotids, openings for .... 33 
Cartilage, sub-nasal 51 
Cams, work cited 79 
Cats , 7g 
Cavum ci anii , 21, 24, 25, 26. 31, 32, 33, 40 
Candal flu rays 84, 85 
tin rays, laminae of 88 
vessels 84 
Ceratodus 19,56 
skeleton of 44 
Ceratohy als ... 55, 73 
Ceratohyals, symphysis of 74 
Cerebrum 34 
Characinidae 35 
Characinides 24, 35 
Characinids 41 
Chondrocranium 51, 56 
Chondostroma nasus 38 
Chorda in fishes, conically-pointed piece of. 18 
Chromides 39 
Clarias 56 
Page. 
Clarias, skull of 47 
Clavicle 78 
Clavicula 78 
Clupeidae 27 
free occipital arches in 13 
Olupeoid teleostei 44 
Comparative anatomy of Owen 44 
Converging development 39 
Cope. E. D., work cited 81, 89 
Copula 80 
Coracoids 77,78,79 
Cornell University 87 
Coronoid process 48, 49 
Cranial vault 69 
Crauii cavum 34 
Cranium 21, 59, 64 
base of 50 
bones of 45 
in amia, number of vertabrse in.. 15 
of amia, three verterbrae in ... 16 
postero external angle of 61 
Cubital 78 
Cuvier 78 
Cuvier, G., and Valenciennes, A., work 
cited 89 
Cuvier, suprascapula of 5 
Cuvier, work cited 75, 81 
Cycloid scales .... 57 
Cyclostomata .. 17 
Cyprinodonta 39 
Cyprinoidei 57 
Cyprinoides 24 
Cyprinoids 35, 41 
nasal aperi ures of the 37 
Day, F., work cited .1 89 
DeKay, woi k cited 81 
Dental area 64 
Dentary .. . . 48,75,76 
sympbysial end of \ 48 
Dentine tula lets 7 
Dermal bones 7, 8,11, 40 
relations with the true skele- 
• ton 8 
Dermo-bones, posterior medial 5 
Dermo-etlimoid 46 
Dermo-plates 46 
Denno-supraoccipital 45 
Dennopostfrontal 8 
Dermoprefrontal 8 
Dfpnoans, elements of the giidje of 78 
girdle in 77 
Dipnoi 11,18,19,29,38 
inner nasal opening of 37 
shoulder girdle of 77 
Dobson, G. E., work cited 89 
Dogfish 80 
Dorsal tin, inter spinous bones after 86 
Dorsum of the trunk, muscle of the 11 
Dumeril, Aug 88, 89 
DumOril, work cited 80, 87 
Ear capsule 61 
Ear, middle ... 30 
Ectocoracoid 77, 78 
Ectopterygoid 53, 73 
Edinburgh 43 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
126 
Page. 
Elasmobranchs 82 
Elopidas 5u 
Elops 57,82 
Entopterygoid 53, 73 
Epicoracoid , 77 
Epihyal 55, 73 
Epiotic 50,51,52,60,61,63,78 
Epipleural appendages 88 
Episthotic. 13 
Epithelium 9 
Esox 1 56 
Ethmoid 6, 7, 46, 51,56, 62, 63, 06, 71 
Ethmo-parasphenoidal suture 63 
Eustachian tubes 29 
Exoccipital.. 5,10,13, 24, 25, 50, 51, 59, 60, 61, 64, 65, 
69, 70 
facet 59 
Exoccipitals in large specimen of Amia... 12 
External rectus muscle, origin of 32 
Extrascapula ... 7 
Eye-muscle canal 64 
Eye-muscles 21, 23, 3’, 33, 60 
recess for the 26 
Facial, branch of 20 
Facial nerve 20 
distribution of 21 
main trunk of 31 
Facial nerves, fascia of 31 
Fat tissue, interdural lymphatic 24 
Fin-rays, arrangement of osseous 88 
of amia, boundaries between the.. 12 
First vertebra in higher lisnes, anterior as- 
pect of 19 
neutral arch of the 12 
Fish Commission 1 
Fishes, aquasducti in higher 41 
cranium of higher 17 
development of the nasal organ in.. 38 
l ow sound-waves reach the laba- 
rynth in 26 
hyomandibular of 31 
labyrinth in higher. .. 25 
nasal region in higher 41 
nasal valves of 38 
posterior nasal aperture of 37 
ramus palatinus in higher 42 
sound conducting media in 28 
specialized osseous 56 
tails of 84 
the girole in 77 
the vertebral column of 83 
vomerine and palatine teeth of. 10 
vomers of 10 
Florida ... 44 
Foramen, acusticus 25 
magnum 23, 51, 60, 61, 70 
opticus ... ...... 21 
Forearm 77 
Fore-gut, teeth upon the mucous membrane 
of ID 
Foster, M. and Balfour, F. H., work cited. 89 
Franque, H 1 
Franque, Henricus, work cited 12,13, 43,44, 45, 80, 
82, 8"., 86, 87, 88, 89 
Frog 57 
Page. 
Frog, nasal capsule of 23, .'3 
skull, development of 53 
1'iomal, mucous c ’iials of the 23 
Frontal plates 70 
Frontalia .... <j 
Frontal.- 5,6,7,22,46,51,58,62,69.70 
Ga iidae 35 
the in e calare in 13 
Gadus 01 
Kaniceps fuscus 35 
Ganglionic cells 34 
Ganoid plates 45,50,53 
sculpturing of 3 
Ganoidei 57 84 
Ganoids 19, 23, 35, 37, 40, 41,42, 54, 56, 57, 78, 82 
American 57 
cranial osteology of living 43 
Crossopterygian 57 
extinct 82 
nasal pit of 37 
olfactory nerve in 35 
olfactory organs of 36 
Gar-pikes 80 
Gegenbaur 4, 37,43, 60, 78 
Gegenbaur, C., work cited. . 19,33,34,37,84,89 
Gegenbaur on the vagus 11 
Gegenbaur, Privy Counselor, professor 2, 3 
Generative o gans 57 
Geoffroy. omolita of 5 
Gill 67,77,80,122 
Gill cavity 2? 
anterior, superior apical recess 
of 27 
how sound-waves reach the laby- 
rinth from 28 
in polypterus .... 30 
relations of the labyrinth to 27 
sacculus relation to 27 
utrieulus relation to the 27 
water- contained in 28 
water present in 27 
Gill cleft 29 
function of the anterior 29 
Gill, Professor 61 
Gill, T. N., work cited .... 65, 70, 81, 89 
Gill rakers .. 75 
Gadidte spinal nerves in the 16 
Glossohyal 55 
Glossopharyngeal foramen 14 
nerve of Amia.. ... 14 
Glossopharyngeus, foramen for the exit of 
the 20 
Goodsir, John, work cited 89 
Gottsche, C. M.. work cited 89 
Great Lakes 80 
Gular plate 70 
Gunther 77 
Gunther, work cited 19,44,81,89,90 
Gyrnotides 24 
Haunal spines 85 
Halecnmorphi 44 
Hnsse 28 
Hasse, C., work cited 27 
Haversian canals 7,8 
Hearing, organ of 28 THE OSTEOLOGY OF AMIA CALYA. 
Page. [ 
Haemal arches 68 j 
Hertwig, work cited 9,10,19 
Hexanchns 33 
Higher animals, generation of new nerves 
in 15 
Hollaid, H., work cited 90 
Holocephals 35 
Humeral - 78 
Huru6ral cartilage 77 
Humerus 77,78 
Humjihrey, G. M., work cited 90 
Huxley 43,82,88 
Huxley, Professor, work cited.. .44, 76, 81, 84, 87, 90 
Hydrocyon 35 
bulbus in 35 
Hyoid arch 74, 80, 81 
Hyoid, articulation of 55 
Hyoidean series, ceratohyal of 49 
epihyal of 49 
hypohyal of 49 
interhyal of 49 
Hyomandibular ... 30, 53, 54, 55, 56, 64, 66, 72, 73 
articular facet for 40, 72 ! 
articulation for the 20 i 
cleft . 29,31 
facet 25 j 
Hypercoracoid 78 
Hypocoracoid 78 | 
Hypohyal 55 ; 
Hypophysis > 21 
cerebri 32, 41 
Hypural bones 84,86 
Hyrtl, work cit°d „ . 44 
Intercalat e 5,10,13,14,24, 25, 40, 50 
Inter! ®mal spinvs 84 
Interhyal 55,72,73 
Intermaxillary 23, 50 
Interope culum 56, 72 
Interramal space .. 50 
Iuterspinous bones 85 
in Micropterus 88 
Isthmus 80,81 
Jahrbuch, Morphologisches 1 
Jordan .... - — 60 j 
Jordan and Gilbert 44 1 
Jordan and Gilbert, wotk cited 45, 62, 90 
Jotdau, work cited 81 
Jugal bono 56 
Jugular vein 20 
Kolliker 88 
Kolliker, work cited .86, 87, 90 
Labroidse 39 j 
Labyrinth 21 
niche 24, 25 
region ..... 23, 29,40 ! 
region, anterior border of 24 j 
. region of Amia 19 
region, the term 19 
vestibule of the 25 
Lac6p6de, work cited 90 
Lacrymal 71 
Lady fish 66 
Lake-lawyer 80 
Larigerhaus, Paul, work cited 90 
Lamina, perpendicularis 51, 53 
Page. 
Lateral line 7, 77 
Le Conte, Joseph, work cited ... 90 
Lepidos’eus 44, 56, 75, 80, 82, 88 
basioccipital of 18 
interosbital septum in 36 
olfactory nerve in 36 
tail of 37 
the occipital arch in 13 
Leydig, work cited 9 
Linnaeus 80 
Linnaeus, Carl von, work cited 90 
List of principal works consulted 89 
Lobos vasculosos 32 
London . 43 
Lota vulgaris 38 
Liitken, C., work cited 38, 90 
Lymphatic fossa 33 
Lymphoid tissue 33 
Macrodon 5 
Mammals, malleus of 76 
squamosal bone in j .. 77 
Man, petro-mastoid portion of temporal in.. 61 
Mandible 7, 49, 76 
mucus canal of 52 
as articulare oi Teleostean 49 
ramus of 77 
symphysis .> 73 
Maxilla 56 
Maxillary 47, 57, 71 
apparatus, muscular system of .. 31 
Mayer, P. J. C., work cited 90 
Meckelian cartilage 49, 76 
Meckel’s cartilage 48, 49, 56 
Median cartilage 77 
nasal aperture 37 
Medulla oblongata 11,24 
Megalops 57, 62, 82 
alisplienohis of 68 
antero-lateral region of the cra- 
nium of 69 
basioccipital of 69 
coossified vertebra in 70 
cranium of . 61, 67 
epiotics of 69 
ethmoid 68, 71 
exoccipitals of 70 
frontals of 67 
gular plate of 62 
opisthotic of G9 
orbitosphenoid of 68 
paraspheniod of 68 
parietals of ... ... 67 
posterior view of the cranium of. 69 
postfrontal of 68 
prootic of 69 
supraoceipital of 67, 69 
squamosal of 68 
vomer of 68 
Membranous labyrinth, deeription of 25 
Mento-meckelian bone 49 
ossicle. 48,56 
Mesocoracoid 78,79 
Metapterygoid 53,57,67 
ascending process of 54 REPORT OF COMMISSIONER OF FISH AND FISHERIES 
128 
Page. 
Micropterus 58, 60, 
61, 72, 74, 77, 78, 79, 80, 86,110,120 
actinostsof 79 
admaxillary of 71 
angular of 76 | 
ai ticular of 75 
basi sphenoid of 59 j 
bones of skull of 70 
branchial arches of 75 
brancliiostegal rays of * 74 
cranium of 58, 60, 71 
entopterygoid of 72 
epiotics of 58 
exoccipitals 59 
foramen magnum of 59 
glossohyal of 73 
hyoid and branchial arches 
of 73 
hyomandibular 61 
hypercoracoid 79 
hypocoracoid 79 
hypohyals of 73 
infrapharvngeal bones of 75 
interoperculum of 72 
interspinous bones 88 
mandible of 75 
maxillary of 71 
metapterygoid of 72,73 
mucus canals of 58 
nasal of 71 
occipital ribs of 59 
palatine of 71, 72 
parasphenoid of 59 
pariet ils of 58 
pectoral flu of 122 
pectoral limb of 110 
pelvic bones 83 
postfrontal of 58 
posttemporal of 78 
premaxillaries of 71 ; 
preoperculum of 72 
1 prootics of 60 
pterotics of 58 
pterygo-palatine arch of 72 
quadrate of 72 
shoulder girdle of 110 
skull of 116 
squamosal mucus canal of 58 
sqfiamosals of 58 
supraoccipital of 61 
supr apliaryngeal bones of 75 
the opercular group of bones 
in 71 
third hypural plate of 86 
thirty-two vertebrae in 88 
vertebral column of S3 
vomer of 60 
Miklucho-Maclay, work cited 90 
Milne, Edwarde A., work cited 90 
Minnesota 44 
Mississippi River 80 
Mivart, Saint George, tfork cited 90 
Moreau A., work cited 90 
Mormyridse . 35 
Morphology of the skull of the salmon 7 
Page. 
Mouth, cavity of the 8 
mucous membrane of the 9, 20 
Muco-dermal bones 77 
Mucus canals 6, 7, 8, 52, 62, 63 
importance of 42 
ramifications of smaller 7 
Mudfish 80 
teleotemporal of 78 
Muller, J., description of polypterus by 44 
Muller, Johannes, work cited 2,28,44,81,90 
Muraenoids . 38 
Muscles, the tw o oblique 23 
Narial apertures, posterior 46 
depressions..., 5 
Kasai alar cartilage 38,39 
apertures — 38 
bridge 38 
capsule 37, 53, 59 
cavity 37 
fossai 23, 34 
region 21 
Nasals 6 7, 46, 51 
Naso-labial groove 37 
Nerve, facial 54 
first division of 53 
second division of 53 
third division of 53 
trigeminal 59 
Nervus abducens 32 
foramen of exit for 33 
Netherlands, Arch. F., zoolog 42 
Neural arches 85, 88 
canal 85 
N eurilemma ■... 34 
Newberry, J. S., work cited 90 
New Orleans 1,44,102 
Nomenclature adopted 77 
Notidanides. 38,40,42 
hyomandibular articulation in.. 41 
nasal aperture in 37 
rostra of the 41 
Notidanus 57 
Notochord 18, 84, 86, 88 
cartilaginous sheath of 88 
sheath of 84 
Oberes stuck 78 
Objects in nature, lateral view of 66 
Occipital arch 24, 50 
anterior 12 
spinal processes of ...: 12 
posterior 12 
nerve, foramen of, exit of the 
first 16 
region, anterior part of 24 
arrangement of the nerves in. 18 
cranial bones of 61 
Occipitale laterale 13,14,16, 24 
foramen in 14 
Occipitalia lateralia 16,17 
crests of 24 
cover bone of 24 
Occiput 11 
of amia, base of the 12 
Oculomotorius 23 
Olfactoria foramina 34 129 
THE OSTEOLOGY OF AMIA CALVA. 
Page. 
Olfactory, course of the fibers of 34 
membrane 35 
mucous membrane 34, 36 
mucous membrane, bulbi olfac- 
torii of 34 
nerve 34, 35,36, 51, 59 
course of 42 
of Amia, passage of 
the 10 
nervelets 35 
region 34 
Opercular apparatus 28 
bones 28, 56, 79 
modified branchiostegal 
rays 72 
Operculum 28, 53, 55, 56, 71, 72 
Ophidia 53, 56 
Opisthotic 10, 50, 51, 52, 56, 58, 61, 64, 78 
Optic foramen 22, 31, 66 
nerves 53,70 
Opticus nerve 32 
Orbit 66 
upper margin of 20 
Orbital cavity 66 
muscles 53, 61 
Orbitar process 49 
Orbitosphenoid .. .35, 51, 52, 53, 56, 58, 61, 66, 69, 70 
Orbito-sphenoids, circular 70 
Oreynus thynnus ... 59 
Ord, ¥m. M., work cited 91 
Os articulare 77 
lower jaw of 76 
Os coracoidien 78 
Osducarpe 78 
Os linguale 73 
Ossa petrosa — 31 
Osseous fishes, nares in 38 
nasal bones of * 5 
posterior nasal aperture in. 39 
Ossicula auditus 28 
Ossifications, septo-maxillary 56 
Otic bones 56 
region 55 
Otoliths 27 
Owen, Sir Richard 71,77,78 
Owen, work cited 45, 75, 81, 83, 91 
Palatal arch 30 
Palatine 53, 54, 56 
arch 23 
segments of the 10 
teeth of 9 
Palato-pterygoid arcade 49, 53 
Palato-quadrate arch 61, 66, 71, 73 
Palato-quadratum 29 
Paraglenial 77,78 
Parapophyses 84, 85 
Parasphenoid 9,10 
19, 21, 31, 50, 51, 60, 62, 63, 64, 66, 70 
number of vertebrae covered 
by 19 
posterior limbs of 16 
teeth of 8, 9 
Parietal 6, 7,11,45, 61,69 
dermo-plates 45 
plates 45 
Page. 
Plates, posterior margin of the 13 
Paritalia 4 
Parker 43, 60,71,77, 78 
Parker, W. K., and Bettany, G. T., work 
cited 91 
Parker, W. K., work cited 53,61,91 
Pecten 12 
Pectoral fin 79, 81, 82, 86 
limb, combined actinosts of 83 
rays 83 
Pelvic bones .. 80 
bones, position of 82 
fins , 82 
Perea 88 
Perea, Americana 60, 75,108 
Perch 75 
American 60 
cranium of a 108 
Perenni-branchiates 38 
Periorbital, lymph sinuses 33 
Periotic mass 61 
Petrosal 13,14, 20, 26, 50 
openings near the anterior margin 
of . 20 
Philadelphia transactions 53 
Physostoma 40 
Pbysostomi 2 
Pia mater 34 
Pigment cells 8 
Pike 38,56 
cartilagenous rostrum of 23 
free occipital arches in the 13 
prenasal rostrum in 53 
vomer of 10 
Pisces, muscular system of 3 
nervous system of 3 
organs of sense of 3 
visceral skeleton of 3 
Piscine skull, relation of the various hones 
of 74 
Pituitary fossa 53 
Polypterus 6,19, 30, 56, 57, 86 
a free occipital arch in 13 
ethmoid of 53 
hyomandihular cleft in 30 
Leydig’s investigation of 9 
gular plates of 50 
Pomacentrides 39 
Postero-alar projections 63 
Posterotemporal 78 
Posttemporal 61 
Postfrontals . 6, 8,10 
20, 22, 24, 25, 50, 51, 58, 61, 62, 64, 66, 67, 71 
Postoral arches 40 
Postorbital processes 10, 20, 41 
Postorbitals 46 
Posttemporals 45, 77 
Posttemporal elements . 78 
Postclavicles 78 
Postzygapophyses 65, 88 
Precoracoid 78 
Prefrontal 6, 8,10, 21, 24, 50, 54, 60, 6? fC, CD, 71 
Premaxillae 51, 56 
teeth on 54 
Premaxillary 50 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
Page. 
Prenasal bone 6 
process 51 
Preoperculum 7, 46,47, 48, 49, 53, 56 
Preorbital 7,46 
Prezygapophyses 88 
Primoidal cranium 11, 22, 31, 39 
cartilage of 13, 38 
cartilaginous portion of 
the 14 
composition of 17 
of Amia, posterior lat- 
eral angle of 13 
ossifications of 8,23 
relations of the squamo- 
sal to 11 
Primoidal skull, lateral angle of the 10 
Pro-atlas 18 
Proceedings of American Association of 
Science 80 
Process, anterior clinoid 53 
Prolongation of notochord 88 
Prootic .. 51, 56, 59, 60, 61, 64, 66 
Pro-otic bridge 53, 56 
Proscapula 78,79 
Protractile snouts, fishes with 71 
Pterotic 60, 61, 78 
Pterygoid 54 
teeth of 9 
Quardrate 48, 49, 53, 55, 72, 73, 77 
bone. 76 
Radius 78 
Ramus lateralis nervi trigemini 14 
palatinus nervi facialis 16 
Rana 56 
Recessus cochlearis 24 
Recti externi 32,33 
Rectus externus 23 
Reference letters used in the plates, expia- 
tion of 92 
Reptiles, surangular of 75 
Respiratory apparatus 73 
Rhinal chamber 10 
Ribs 84, 85, 88 
Rolleston, work cited 81 
Sacculus 24, 25, 27, 28 
recess for 24 
Sagemehl, Dr. M 1,11, 43, 45,46, 50, 51, 57 
Sagemehl. nomenclature of cranial elements 
used by 52 
Sagemehl, occipital arches of 51 
Sagemehl, occipitale laterale of 50 
St. Hillaire, Geoffrey, work cited 28 
Salamanders, larval 56 
Salmon''! 84 
Salmon’s skull 60 
Salmonid®, free occipital arches in 13 
Sapraclaviculare 78 
Scales 80 
Scapula 77, 78 
Scapulaire 78 
Scombridas 59 
Scopelus 25 
Scyllia, skull in the 40 
Scy Ilians 37 
ScyIlium . 40 
Page. 
Selachians 2,18, 30, 34,35, 37, 40, 57 
auditory apparatuses 30 
canalis transversus of 33 
exit of the cranial nerves in 26 
facial nerve in 31 
first spinal nerves in the 18 
hyomandibular articulation in .. 41 
hyomandihulai1 cleft of 29 
nasal alar cartilage of 37, 41 
nasal apertures in 41 
nasal valves of 38 
occipital region of the 14 
parietal grooves in 41 
posterior arches of 40 
ramus palatinus in 20,42 
region of the labyrinth of 40 
skulls of 18, 21, 39 
sound-conducting apparatus in 39 
subcranial canal of 33 
teeth in 19 
the cavity of the labyrinth in... 25 
Selacliii 23, 25, 28, 39 
cranium of 17 
eye supports in the 23 
nasal valves in 38 
optic foramen of . 41 
primoidal cranium in 17 
tail of 84 
transverse canal of 34 
Sella turcica 32 
Semicircular canal, anterior 25 
outer 25 
posterior 25 
superior vertical 61 
Semi-occipital arch, a third anterior 16 
Septomaxillare 23 
Septomaxillaries .' 23 
Septomaxillary 50, 53, 54 
Shads . 24 
Shoulder-girdle 5, 50, 81 
nomenclature of 77 
Shufeldt, nomenclature of cranial elements 
used by 52 
Shufeldt, R. W., work cited 59, 91 
Siluroidei 56, 57 
skull of 47 
Siluroids 11, 35 
tail of 87 
Siren 56 
Skeleton of osseous rays '... 84 
Skull, cover-bones of 78 
how many metameres contained in .. 17 
labyrinth region of 30 
Selachian 17 
three vertebras coossified with 17 
true ossifications of 9 
vertebral theory of 17 
Smithsonion Institution 1, 77 
Snakes 30 
Southern California 62 
Spangenstiick 78 
Spatularia 44, 56 
Speitzloch canal 29 
Sphenotic 52, 56, 61, 66 
Spinal canal 88 THE OSTEOLOGY OF AMIA CALVA. 
Page. 
Spinal column 61 
extremity of 84 
marrow, anterior end of A 24 
Spirales . - , 57 
Splenial 48, 49 
dentigerous 56 
teeth of 9, 49 
Squamosals 5, 7 
11, 20, 24, 45, 47, 61, 62, 64, 65, 66, 69, 77 
Squamosum, posterior lateral angle of the.. 13 
Stannius 5, 35, 80 
Stannius, H., work cited 16, 34, 91 
Stannius, omolita of 5 
Sternohyoid muscles 74 
Sternum 77, 78, 84 
Stohr, work cited 18 
Stohrs, parasphenoid of 19 
Stylohyal 73 
Subcranial canal, anterior entrance of the.. 33 
Gegenbaur, phylogenetic 
origin of 33 
Subnasal lamina 56 
Suboperculum 28,56,72 
Suborbitals 71 
Suborbital chain of bones 53 
Sudis 75 
Supraclavicle 77, 78 
Supraclavicular, inferior limb of the 13 
Supraethmoid 58, 60, 71 
Supralinear ossicles 77 
Supraoccipital 58, 61, 63 
crest 69 
Supertemporals 45, 77 
Suprascapula 7,14, 77, 78 
Suprascapulaire 78 
Supratemporal bone 5 
Surangular. 48 
Suspensorium 72 
Spmphysis 48 
Symplectic 49, 53, 55, 56, 72 
Table, differences in nomenclature 52 
Tail 85 
border of 88 
diphy cereal 86 
heterocercal 84 
homocereal type of 86 
homocercal 57, 84 
masked heterocercal 86 
movements of 86 
structure of 87 
variations in shape of „ 88 
vertebrae of 84 
Teeth 46, 56, 63, 75, 76 
Teleostean fishes 88 
mandible of a 100 
skull of a 57 
upper jaw of a 110 
Teleosteans 5, 20, 22,24,41, 79, 82 
Amia ancestor of the family of.. 36 
epiphyseal ledge of the skull 
cover in 26 
facial nerve in 31 
labyrinth in 26 
posttemporal of 78 
Teleostei 11,19, 21, 22, 25, 26, 61, 77 
Page. 
Teleostei, anterior branch of the mucus ca- 
nal in frontal 6 
crania of 3 
glossopharyngeal nerve in 14 
hyomandibular articulation in 41 
labyrinth of the 25 
olfactory organs of 36 
physostomus 57 
relation of the labyrinth to the 
gill cavity in 28 
subcranial canal of 33 
superoccipital of 11 
the three occipital nerves in the.. 15 
Teleotemporal 78,79 
Teleosts, pelvic bones of 83 
Temporal fossa 11,13, 40, 77 
anterior angle of 20 
Temporal region 77 
Texas 44 
Tiedmann, F., work cited — 91 
Todd, H. L 1, 43 
Trabecular groove 53 
Tractus 34, 35 
Traquair, work cited 13, 44 
Trigeminal nerves, fascia of 31 
nerve, foramen ibr 61 
Trigeminus, first branch of 22 
second and third branches of.. 22 
Trochlearis 23 
Trout 38 
Truncus hyoides mandibularis 31 
Tunny 59 
TJrodela 18, 29 
TJrodela, columella in 30 
Urohyal 74 
Urostyle 84,86,88 
Utriculus inlet 25 
Vagus 18, 51 
foramen. 11,14, 24, 59, 70 
of Amia, foramen for the exit of the. 14 
Valenciennes 80 
Valentin, work cited 91 
Van Wijhe, work cited 1 42 
Ventral fin 83,86 
parietes 84 
Vertebra, first free 85 
neural arch of the first 65 
of Amia, thirty-eighth 85 
thirty-ninth 85 
forty-fifth 85 
centra of 85 
coossification of anterior 17 
in Amia, centrum of the first.. .. 12 
ribs of 85 
Vertebrae 6 
coossified occipital 50 
inferior process of 84 
Vertebral centra, pieces of cartilage on 16 
column 86 
Vertebrata 77 
manual of 44 
Vertebrate animals, development of 39 
Vertebrates, inner nasal apertures of air- 
breathing 37 
sella turcica of higher 31 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
132 
Page. 
Vertebrate skull, morphology of 43 
Virginia 44 
V oderes Stuck 78 
Vogt, Carl, work cited 2,44,81,91 
Vomer 9, 50, 51, 53, 54, 60, 61, 66 
conical teeth of 8 
Vomerine region 63 
Vulpian, A., work cited 91 
Page. 
Walther, J., work cited 10 
Weber, apparatus of 34 
Wiederscheim, work cited 18,10 
Wilder, B. G 82, 87,91 
work cited 80, 86 
Wortman, J. L 1 
Wyman, Jeffries 91 
Zygapophysial processes... 84 [ EXTRACTED FROM THE ANNUAL REPORT OF THE COMMISSIONER 
OF FISH AND FISHERIES FOR 1883. ] 
/ THE 
\ 
\j 
OSTEOLOGY OF AMI A CALVA, 
INCLUDING 
CERTAIN SPECIAL REFERENCES TO THE 
SKELETON OF TELEOSTEANS. 
BY 
R. W. SHUFELDT. 
WASHINGTON: 
GOVERNMENT PRINTING OFFICE. 
1885. US£« 
JO