DESCRIPTIONS 
OF THE 
INFERIOR MAXILLARY BONES 
OF 
MASTODONS, 
IN THE 
CABINET OF THE AMERICAN PHILOSOPHICAL SOCIETY, 
WITH 
REMARKS ON THE GENUS TETRACAULODON, &c. 
ISAAC HAYS, M.D. 
EXTRACTED FROM THE TRANSACTIONS OF THE AMERICAN PHILOSOPHICAL SOCIETY, VOL. IV. N. S. 
PRINTED BY"*.*.. 
JAMES KAY, J UN. AN D 0O., PHILADELPHIA, 
Printers to the American Philosophical Society. 
1833. DESCRIPTIONS 
OF THE 
INFERIOR MAXILLARY BONES 
OF 
MASTODONS, 
IN THE 
CABINET OF THE AMERICAN PHILOSOPHICAL SOCIETY, 
WITH 
REMARKS ON THE GENUS TETRACAULODON, &c. 
BY ISAAC BAYS, M.D. 
EXTRACTED FROM THE TRANSACTIONS OF THE AMERICAN PHILOSOPHICAL SOCIETY, VOL. IV. N. S. 
PRINTED BY 
JAMES KAY, JUN. AND CO., PHILADELPHIA, 
Printers to the American Philosophical Society. 
I 
1833. Descriptions of the Specimens of Inferior Maxillary Bones of Mastodons 
in the Cabinet of the American Philosophical Society, with Remarks 
on the genus Tetracaulodon ( Godman), fyc. By Isaac Hays, M.D. 
Read May 20, 1831. 
MY friend, the late Dr Godman, communicated to the Society about 
eighteen months since, an account of an extinct fossil animal, closely 
resembling the Mastodon in most of its characters, but differing from 
it, in possessing tusks in the lower jaw. This difference Dr Godman 
thought of sufficient importance to constitute a new genus, to which 
he gave the name of Tetracaulodon.* 
The immediate subject of Dr Godman’s description having been a 
young animal,f a distinguished naturalist! of New York suggested the 
opinion that the Tetracaulodon was nothing but the young of the gi- 
gantic Mastodon, and that the tusks were merely milk teeth, which 
were lost as the animal became adult.§ The same opinion has since 
been confidently advanced by others.|| 
Had Dr Godman been able to examine the specimens in our cabi- 
nets with his own eyes, instead of being obliged to rely upon those of 
others, his own memoir would doubtless have contained all the proofs 
necessary for refuting the opinion that he had committed the error of 
* See Yol. III. N. S., p. 478. 
t Dr Godman states, however, that there are two adult jaw bones of the same animal in the 
cabinet of the University of Virginia. Vol. III. N. S., p. 484. 
X William Cooper, Esq. 
§ See Silliman’s Journal, Yol. XIX. p. 159, 160, October 1330. 
|| See Ferussac’s Bulletin for August 1830, &c. DESCRIPTIONS OF INFERIOR MAXILLARY BONES 
describing, as a new animal, the young of a known species. The 
account of the Tetracaulodon was, however, written by the author, 
literally on his death bed.* There is no need of the Society’s being 
reminded of the generous and lofty ambition, by which Dr Godman 
was always actuated, or that he was compelled through life, to struggle 
against difficulties, which no ordinary man could have overcome; and 
they will at once understand his expression to his friends, on announcing 
that he was preparing an account of a new fossil animal,—“ I have 
all my life,” said he, “ been compelled to labour for bread, I shall now 
do something for my fame.” 
These remarks will account for such imperfections as may have 
occurred in Dr Godman’s memoir, as also explain my anxiety to secure 
to him the credit which appears to me to be his due. 
It is not my purpose to inquire into the value of the tusk, in the 
lower jaw, as constituting a generic distinction between the Mastodon 
and Tetracaulodon.f Generic divisions in science are, for the most 
part, as yet too arbitrary—the characters upon which they are founded 
too ill determined—and our materials at present too scanty, to induce 
us to venture any remarks upon this subject, even had we not deter- 
mined to restrict ourselves to a detail of facts. 
A more important subject of inquiry, is whether the Tetracaulodon 
is merely the young of the gigantic Mastodon, and the tusks in its 
lower jaw only milk teeth, which are lost when the animal becomes 
adult and are never replaced. Fortunately the cabinet of the Society 
furnishes us with materials for at once settling this question. It con- 
tains portions of three lower jaws, which I have the honour of exhibit- 
ing, and which will be particularly described hereafter. The first is 
that of a young Mastodon, M. giganteum (Plate XX.), entirely destitute 
of tusks or alveoli for tusks; the two others appertain to aged adult 
animals (Plates XXVIII. and XXIX.), and exhibit distinct sockets for 
tusks. A more complete refutation then of the assertion that the Tetra- 
* Dr Godman died before the number containing his memoir was published, 
t Mr Titian R. Peale, who was the first naturalist by whom the Tetracaulodon was seen, 
suggested to Dr Godman that the tusks in the lower jaw might be merely a sexual character. 
It is impossible, in the existing state of our knowledge, and with our present materials, either 
to confirm or positively refute this suggestion. OF MASTODONS, WITH REMARKS, ETC. 
caulodon is only the young gigantic Mastodon, is hardly possible, and the 
merit of having contributed to the Fauna of this country, one of its 
largest antediluvian animals, is confirmed to Dr Godman. 
The object which originally prompted this communication, being 
thus accomplished, I might here close it; but from the great number 
of specimens which I have been so fortunate as to have had oppor- 
tunities of examining (about forty lowrer jaws, and upwards of two 
hundred teeth), some facts have been presented, to which my friends 
attach so much interest, as to induce me to lay an account of them be- 
fore the Society. 
The first specimen I shall describe is a fragment of the left side of 
the lower jaw, consisting of the ramus, chin and portion of thecoronoid 
process. (Plate XX., fig. 1 and 2.) This fragment is sixteen inches 
long, and weighs nine pounds. The teeth, as well as the loose tex- 
ture of the bone, show it to have belonged to a young animal. The 
condyloid process and angle of the jaw are deficient, and the chin is 
slightly broken, so that it is impossible to determine whether it had 
the foliated termination so conspicuous in the adult. (Plate XXIII., s.) 
The coronoid process rises nearly perpendicularly as in thegiganteum; 
but the ramus of the jaw is rather more cylindrical than in the adult 
of that species. 
This fragment contains two teeth. The posterior one (Plate XX., d) 
had just commenced to pierce the gum; its crown is perfect, but its 
roots are not yet formed. This tooth is four inches and one-tenth* 
long, and two inches and seven-tenths broad. It has three wedge- 
shaped denticules, each of which is divided, by a longitudinal groove, 
into two processes, the inner of which is somewhat the wider; and 
each of these processes is superficially divided into two or more points 
—the exterior points being the largest. 
The anterior tooth (Plate XX., c) resembles that just described in its 
general characters; its crown is, however, somewhat worn, particularly 
its anterior points. Its length is three inches and three-tenths, its 
breadth is two inches and five-tenths. 
* All the measures were taken with callipers DESCRIPTIONS OF INFERIOR MAXILLARY BONES 
Anterior to this tooth are three alveolar depressions (Plate XX., 
m, n, o) which mark the place of teeth which have been lost. 
Beneath the anterior socket is a foramen for the passage of blood- 
vessels and nerve. (Plate XX., fig. r.) At the anterior portion of the 
chin are two foramina for the same purpose: that on the left side is 
lower and larger than the other, pyramidal, and at a short distance bi- 
furcates. A fine needle may be passed some distance into each of these 
divisions. 
In one of the lower jaws of an adolescent Mastodon in the Finnel 
collection at New York, the foramen in the chin is two lines in diame- 
ter and passes directly into the large foramen in the ramus of the jaw7 
occupied by the maxillary nerve and blood-vessels. 
The next specimen to be noticed, is a fragment of the right side of 
the inferior maxillary bone of an adolescent gigantic Mastodon, (Plate 
XXI.) belonging to the splendid Wistar Museum of the University of 
Pennsylvania. This fragment is two feet five inches long. The 
general form of this jaw is similar to that of the gigantic Mastodon 
represented in Plate XXIII., but the ramus is rather more cylindrical, 
in which respect it resembles the specimen just described (Plate XX.). 
The upper portion of the coronoid, and the condyloid processes are de- 
ficient, as also the angle. The chin is also broken, but there are 
manifest indications of an expansion similar to that represented in 
Plate XXIII., s. Just above the base of the ramus internally are a 
number of circular depressions, probably formed by the lobules of 
the inferior maxillary gland. 
This fragment contains two teeth, and anterior to these a portion of 
the alveolus of a third tooth. The anterior tooth (Plate XXI. e) has 
three denticules, writh twro points each: it is five inches and eight- 
tenths long, and three inches and seven-tenths broad. The posterior 
tooth (Plate XXI. f) has five denticules or pairs of points, and a trifid 
heel. This tooth is eight inches and one-tenth long, and four inches 
and three-tenths broad. 
The cabinet of the Society does not contain any specimen of the lower 
jaw presenting all the characters of the Mastodon giganteum, except 
a small fragment represented in Plate XXII. This fragment is twelve OF MASTODONS, WITH REMARKS, ETC. 
inches long, and consists of a portion of the ramus of the jaw, with the 
base of the coronoid process. It contains one tooth, the posterior mo- 
lar. This tooth has five denticules with two points each, and a heel; 
it is six inches and nine-tenths long, and three inches and eight-tenths 
broad. 
I have the pleasure, however, of exhibiting to the society, one of 
the most perfect specimens of the lower jaw of this species, that has 
as yet been obtained. (Plate XXIII.) This jaw belongs to the Balti- 
more Museum. It is the one dug up by the late Mr Peale on the 
farm of Peter Millspaw, twenty miles west of the Hudson, which is 
described by Mr Rembrandt Peale in his “ Narrative of the discovery 
and exhumation of the skeleton of the Mastodon,”* and drawings and 
a description of which were communicated by Mr Peale to Baron Cu- 
vier, and from which the latter drew many of his characters of this 
interesting animal. When found this jaw was perfect; but about two 
years since it was unfortunately broken by accident. The largest 
fragment, consisting of the whole right side of the jaw, the coronoid and 
condyloid processes, the chin and nearly two inches of the left side, all 
i n a remarkably fine state of preservation, are represented in Plate XXIII. 
The length of this jaw is two feet six inches and a half, the height 
of the coronoid process above a line drawn along the base of the jaw 
fourteen inches and a half. 
The articulating surface of the condyloid process is divided by a 
superficial groove (a?) at about two-thirds of the distance from its inner 
edge. The direction of the condyle is inwards and rather forwards. 
The coronoid process rises nearly perpendicularly; the upper part 
curves somewhat outwards; it is one inch and a half higher than the 
condyloid process. 
Just below the condyle a ridge (t) commences, which, after passing 
downwards and a little forwards a short distance, becomes nearly hori- 
zontal, and above this is a considerable depression, an inch in depth at 
its deepest part. 
That portion of the jaw which is covered by the masseter muscle, 
is much flattened and rough; the angle is also very rough. 
* Copied in Godman’s American Natural History, Vol. II. p. 211. DESCRIPTIONS OF INFERIOR MAXILLARY BONES 
The ramus of the jaw is slightly flattened on its external aspect, 
and somewhat excavated on its internal one. The anterior maxillary 
foramina are two (Plate XXIII., fig. 1,/>, q); there are several smaller 
foramina near the chin for the passage of the blood vessels and nerves. 
The chin terminates in a remarkable expansion, the edges of which 
are exceedingly rough. (Plate XXIII. s.) There are no alveoli for 
tusks, nor any trace of there ever having been any. 
This jaw contained but one tooth in each side. The sockets for the 
molars anterior to these are completely filled up. The tooth which re- 
mains (the last molar) was somewhat injured by the accident to which 
we have already referred, but it appears to have had ten points and a 
heel. The direction of this tooth in the jaw is outward anteriorly, 
as is seen from fig. 2. 
The foramen for the inferior maxillary nerve and blood vessels is 
just below the condyle internally (fig. 2, y), and is one inch and a quar- 
ter in diameter. 
On the upper surface of the ramus, just at the base of the coronoid 
process, is the commencement of a small groove, which immediately 
divides and diverges. It is evidently caused by a blood vessel; and 
we mention it because a similar groove occurs in the fragment repre- 
sented in Plate XXII. It is not to be found in any other specimen in 
the collection.* 
The lower jaw represented in Plate XXIV. differs considerably in its 
form from the jaws of the M. giganteum we have described. Its base 
is more curved antero-posteriorly—the external aspect of its ramus is 
more flattened, and that portion of the jaw covered by the masseter 
muscle less so. The groove for the tongue is deeper and narrower; 
and the chin appears pointed, but the specimen being partly worn it 
is impossible to determine the exact form of this part. 
* There is in the Cabinet of the Lyceum of Natural History of New York, a fragment of 
an inferior maxillary bone, which agrees in all its characters with that just described, except 
that the direction of its condyle is inwards and backwards, and that its posterior molar has but 
four denticules. This bone was found in New Jersey, and is figured in Mitchell’s edition of 
Cuvier’s Theory of the earth; and copied into Cuvier’s Ossemens Fo s sites ; Grand Masto- 
donte, Plate III. fig. 5. OF MASTODONS, WITH REMARKS, ETC. 
The posterior molar (Plate XXIV. f) has but eight points, and the heel 
is broad, whilst in our specimens of the M. giganteum the posterior 
molar has ten points and a mammillaform heel. The direction of the 
teeth is also very divergent anteriorly. Are these differences suffici- 
ent to indicate its belonging to a different species from the M. gigan- 
teum ? 
There is, in the cabinet of the Society, a portion of another jaw, 
consisting of the left ramus, containing two teeth, and the chin ; which 
is entirely similar to the above in its characters, but somewhat dis- 
torted, no doubt from injury when the animal was young. There is 
another specimen resembling the above in its general characters, among 
the lower jaw bones of Mastodons belonging to J\ P. Wetherill, Esq. 
and which are deposited in the valuable cabinet of the Academy of Natu- 
ral Sciences of this city. This fragment, however, has had the teeth 
broken out.* 
The cabinet of our Society contains a portion of an inferior max- 
illary bone, (Plate XXV.) which differs in its form from any of those 
hitherto described. This fragment consists of the chin, the right ramus, 
with the posterior molares, and a portion of the left ramus. The 
anterior molar (Plate XXV. e) has three denticules with two points 
each; the posterior (fig. f) has four denticules, with two points 
each; and a ridge posteriorly. The ramus of this jaw is straighter, 
and more cylindrical; the height from the base to the edge of the al- 
veole is less; the groove for the tongue broader and shallower; and 
the direction of the teeth less diverging than in the maxilla figured in 
Plate XXIV. The crowns of the teeth are also less elevated in the 
former than in the latter. 
In the collection deposited by Mr Wetherill in the Cabinet of the 
Academy of Natural Sciences, there is a fragment of a lower jaw, 
which exhibits the same characters as the one just described. This 
fragment consists of the chin, about eight inches of the left and twelve 
inches of the right ramus. The alveolar processes are much broken, 
and the teeth are lost. 
* This jaw was exhibited to the Society. 8 
DESCRIPTIONS OP INFERIOR MAXILLARY BONES 
The inferior maxillary bone described by Dr Godrnan* is very 
accurately represented in Plate XXVI., fig. 1 and 2. The chin, the right 
ramus and a portion of the coronoid process, and about three-fourths 
of the left ramus are perfect. The mental ridge, each side of the labial 
groove, is sharp and smooth, without that remarkable foliated expansion 
so conspicuous in the M. giganteum (Plate XXIII. s). In the left ramus 
there is still the first deciduous tooth (Plate XXVI. fig. 2, a); on the right 
side the corresponding tooth has fallen out, and its socket is partly obliter- 
ated. This tooth (fig. 2) is one inch and five-tenths long, and one inch 
and one-twentieth broad; its surface is considerably worn, most so an- 
teriorly. It had four points; anteriorly there is a fold of enamel which, 
commencing at the external edge of the base of the crown and passing 
upwards and inwards, terminates in a point; posteriorly there is a some- 
what similar and rather broader fold of enamel. Anteriorly the crown 
is rounded; posteriorly it is flattened from contact with its successor; 
its grinding surface is considerably worn. It has two roots, one ante- 
rior, the other posterior. 
We have seen in the cabinet of William Cooper, Esq. of New York, 
a fragment of a lower jaw containing one of these teeth exceedingly 
perfect; its points are scarcely perceptibly worn. Another specimen 
is in the cabinet of the Academy of Natural Sciences.f 
The second tooth (Plate XXVI. b) is one inch and eight-tenths long, 
and one inch and eleven-twentieths broad. This tooth, like the preced- 
ing, had two denticules, with two points each. On the anterior of the 
crown there is a flat fold of enamel similar to that on the first tooth. 
This tooth has also a heel which rises highest towards its inner aspect, 
forming a small fifth point. The grinding surface of this tooth is 
considerably worn. This tooth like the preceding one has two roots; 
one anterior, the other posterior. 
In the Finnel collection there is one of these teeth; it is one inch 
and seven-tenths long, and one inch and five-tenths wide. 
* Vol. III. p. 478. 
t This tooth is described in the “ Fauna Americana,” as appertaining to a new species of 
Tapir to which the name T. Mastodontoideus is given. Mr William Cooper was we believe 
the first to detect this error; we have carefully examined the tooth, and there can be no doubt 
of its being the first milk tooth of the animal we are describing. OF MASTODONS, WITH REMARKS, ETC. 
The third tooth (Plate XXYI. c) is three inches and one-tenth long, 
and two inches and two-tenths broad. This tooth has three denticules, 
with two points each. On the anterior surface of the crown, it has a 
fold of enamel rising up in a small point; and along the base of the 
crown posteriorly there is an horizontal ridge, consisting of a number 
of very small mammillaform processes. This tooth has three roots cor- 
responding to its denticules. 
The fourth tooth (d) is three inches and seven-tenths long, and two 
inches and eight-tenths broad : it has three denticules, each of which 
is divided by a deep groove into two rather flattened points, of which 
the inner is the broader; each of these is again superficially divided 
by a slight groove. At the base of the crown, both anteriorly and 
posteriorly, there is a ridge of very small mammillaform points. Each 
denticulehas on its external point, both on its anterior and posterior sur- 
face, a ridge of enamel, which commences at the base of the process 
near the central groove and passes upwards and outwards. This ridge 
appears to exist on all the teeth until it is worn down by use, and we 
find traces of it also in the teeth of the M. giganteum. The crowns 
of all the teeth rise on their inner surface nearly perpendicularly, but 
on the outer side they slope obliquely inwrards. 
The tusk belonging to this jaw is so accurately described by Dr God- 
man, and so correctly represented in the plate to his paper, that there 
is no necessity for my doing more than to refer to it. (See Vol. III. 
N. S., Plate XVIII. fig. 2.) 
The tusk represented in Plate XXVI. fig. 3, is that of an adult ani- 
mal. It is eleven inches long, and its largest diameter is two inches, 
its section is oval. This tusk consists of a central column composed 
of thin plates nearly parallel to its base; the whole covered with a coat 
of enamel, which becomes very thick towards its projecting extremity. 
The enamel is entirely worn off* to the termination of this tusk, and even 
the central bony column is evidently worn down and smooth, as if from 
use by the animal; it is also worn at one side. This tusk belongs to 
the collection of J. P. Wetherill, Esq.* 
* There is in the cabinet of the Academy of Natural Sciences, deposited by Mr J. Fisher, 
by whom it was obtained at Big-bone lick, a tusk much smaller than the one we have de- 
scribed—it is also much less perfect. DESCRIPTIONS OF INFERIOR MAXILLARY BONES 
The next specimen we shall describe is the right side of an inferior 
maxillary bone, in a remarkably perfect state of preservation, belonging 
to the cabinet of the Society. (Plate XXVIJI.) 
The condyloid process in this jaw is considerably higher than in the 
M. giganteum (Plate XXIII.). The direction of the condyle also dif- 
fers, being inwards and backwards. 
The coronoid process appears to have risen nearly perpendicularly, 
but its anterior edge and termination are broken. The semilunar notch 
was evidently deeper in this than in the M. giganteum, though its exact 
form cannot be determined in its present injured condition. 
The posterior angle is much rounder than in the M. giganteum. 
The outer surface, where the temporal muscle wTas inserted, is very 
rough, being over a considerable space quite tuberculated; and there is 
a distinct semi-circular ridge of these rough elevations, as will be seen 
on reference to the drawing. (Plate XXVIII. fig. 1, t, t7, t7/.) Im- 
mediately anterior to this semicircular ridge, there is an excavation, 
distinctly striated with muscular impressions («). The ramus is 
remarkably cylindrical, and its base much more curved than that of 
the M. giganteum (Plate XXIII.). The anterior mental foramen (g) 
is smaller, and nearer to the upper edge of the jaw, than in the other 
specimens, and the posterior mental foramen is larger than in any of 
the specimens hitherto described, its largest diameter being nearly 
nine-tenths of an inch. 
The ridge at the side of the labial groove is broken, but it appears 
to have been expanded ; whether or not, as in the M. giganteum, and 
with irregular terminations, it is of course impossible to divine. 
This specimen contains but a single tooth. This tooth is six inches 
long, and three inches and four-tenths broad. It has four denti- 
cules with two points each. The enamel on the posterior face of the 
crown is broken off, and the characters of the heel cannot conse- 
quently be determined. The grinding surface of the crown is some- 
what worn, and presents the same arrangement of enamel as in the M. 
giganteum. 
In the chin there is a small part of the alveole of the tusk remaining. 
The direction of this alveole is outwards and considerably downwards. 
It has been found impossible to give a good view of this alveole in the 
plate, but its position is marked by the dotted lines representing a tusk. OF MASTODONS, WITH REMARKS, ETC. 
In the cabinet of the Society there is another fragment of a lower 
jaw, but of the left side, in all respects similar to the preceding, though 
much less perfect. The upper parts of both the condyloid and coro- 
noid processes are deficient, but the anterior edge of the latter is more 
perfect than in the preceding specimen, and rises nearly perpendicularly 
from the ramus, The chin in this specimen is entirely deficient, as is 
also the whole of the inner table of the ramus, so that the maxillary canal 
is laid entirely open. This bone must have belonged to an animal nearly 
of the same age as the preceding, or perhaps somewhat younger; the last 
molar, as is seen from the alveole, for the tooth is wanting, not having ad- 
vanced by upwards of an inch as far forward as that in the former jaw. 
Whether or not the specimen described by Dr Godman, and the jaws 
last noticed belong to the same species, cannot be determined positively 
without further specimens. The jaw next to be described, however, 
exhibits differences, which would justify the suspicion that it is spe- 
cifically different from either. 
This specimen is represented in Plate XXIX. It consists of a 
portion of the right ramus of the lower jaw, twenty-two inches and 
a half long. It contains a single tooth, the posterior molar. 
The exterior aspect of this jaw, at its angle, is entirely smooth, without 
any of the rugosities presented in the two preceding specimens. Be- 
tween the posterior molar and the coronoid process there is a large 
smooth excavation, x. The ramus of this jaw is much less cylin- 
drical than that of the species figured in Plate XXVIII., it is much 
flattened on its exterior aspect, and its base is almost straight. The 
posterior mental foramen is exceedingly large, upwards of one inch and 
a quarter in diameter. The posterior molar is seven inches and two- 
tenths long, and four inches and one-tenth wide; it has eight points and 
a broad heel consisting of a row of small mammilla, four of which on 
the inside are very distinct. This tooth differs in various particulars from 
the posterior molar belonging to the specimen figured in Plate XXVIII. 
It is one inch and a half longer, and seven-tenths of ail inch wider, the 
denticules are higher, and the inner points much higher above the ex- 
terior ones. Thus in the former, the second denticule (Plate XXVIII. v) 
rises one inch and eight-tenths from its root, and the inner one two inches 
and two-tenths; whilst in the latter (Plate XXIX. v) the corresponding DESCRIPTIONS OF INFERIOR MAXILLARY BONES 
exterior point rises two inches and three-tenths from the root and the 
inner one three inches and three-tenths, making a difference in the 
former of half an inch, and in the latter of one inch and one-tenth. 
The chin in this specimen contains about one half of the alveole for 
the exserted tusk (fig. 2, z). This alveole is rather more than two 
inches in diameter; its direction is outwards and downwards, less 
downwards however than in the preceding species; indeed there is a 
distinct difference in the position of these sockets in the two specimens. 
The base of the socket is smooth and flat, and its position somewhat 
oblique, so that it is rather deeper towards the exterior, than towards 
the interior; it is perforated by two small foramina for the nutrient 
arteries, and the nerves of the tusk. 
It is to be lamented that little positive can be ascertained, as to the 
localities in which the bones belonging to the Society, and which we 
have just described, were found, their position in the soil, &c. All that 
can be collected is, the probability, that they are from the Big-bone lick, 
and that they are those presented by our late president Thomas Jefferson, 
Esq., and which are noticed in the communication of Professor Wistar, 
in Yol. I. N. S., p. 376, of the Transactions. 
Dentition of the Mastodon. 
The specimens we have just described furnish some interesting in- 
formation relative to the dentition of the Mastodon, which we shall now 
proceed to lay before the Society. The form, and differences, succession 
and number of the teeth are all subjects of great interest; and in describ- 
ing them we shall follow Cuvier, adding such additional information as 
our investigations have brought to light. 
The crown of the teeth more or less approaches the rectangular form, 
slightly inclined however to rhomboidal, and rather narrower anteriorly 
than posteriorly. It consists of two substances, the interior osseous, the 
exterior enamel. The crown is divided by deep furrows into a num- 
ber of ridges or denticules, and these denticules are subdivided by one 
or more superficial and narrow processes or tubercles. The outer 
face of the crown rises nearly perpendicularly, the inner face rises ob- 
liquely inwards. In the lower jaw, the outer point is higher than the OF MASTODONS, WITH REMARKS, ETC. 
inner; in the upper jaw it is the reverse. As the teeth are used, their 
points become worn down, and the enamel presents a lozenge form, with 
hone in the centre. The roots of the teeth are formed after the crown. 
With the remains of the animal described by Dr Godman, there were 
found a number of points, evidently parts of very young teeth, of 
which the bodies by which they were to have been connected together 
had not yet been formed. These points are now in the Museum of 
Mr Rubens Peale, New York. 
The number of the roots may be said to correspond to the number 
of the denticules. In the teeth with two denticules, the two roots are 
distinct; in those with more than two denticules, the anterior and some- 
times the second root are distinct, the others are united but marked 
by distinct grooves. The roots are flattened anteriorly and posteriorly; 
externally they are slightly and internally deeply grooved. 
The upper teeth may be distinguished from those of the lower jaw 
by their roots being more divergent laterally, and by their crowns 
being broader. 
The teeth differ from one another principally in their size and in 
the number of their denticules. 
In the species of Mastodon which inhabited this country there are 
three kinds of teeth. 
The first nearly square and having two denticules; 
The second rectangular with three denticules; 
The third longer, generally contracted posteriorly, and having four 
or five denticules and a heel, of various forms. 
The first mentioned teeth are always anterior, next follow those 
with three denticules, and lastly those with four and five denticules; 
but we have never seen those with five distinct denticules in the upper 
jaw, they appear to belong exclusively to the lower. 
In the young jaw described by Dr Godman, we find, 1st, a small 
square tooth, with two denticules; 2d, one rectangular with two den- 
ticules; 3d, a tooth with three denticules; 4th, one rather larger, also 
with three denticules. In the upper jaw there are corresponding teeth. 
Each of the two adult lower jaws having tusks (Plates XXVIII. and 
XXIX.) contains a tooth with eight points; and it is manifest that there 
was a corresponding tooth in the upper jaw. The whole number of 
teeth possessed by the animal described by Dr Godman (Tetracaulo- 
don) is then at least twenty; and we think that it is at least probable DESCRIPTIONS OF INFERIOR MAXILLARY BONES 
that the animal possessed an intermediate tooth between the second 
tooth with three denticules (Plate XXVI. c/), and that with four denti- 
cules (Plate XXIX./), for we cannot believe the former tooth cor- 
responds with that represented in Plate XXVII. e. Should we be 
correct in our views, this animal possessed three teeth, with three den- 
ticules in each side of each jaw, making the whole number of teeth 
twenty-four; but to render this certain would require specimens of 
intermediate ages to those hitherto described. 
Cuvier attributes to the gigantic Mastodon but sixteen teeth, eight 
in each jaw; of these teeth he saw the three posterior only of each side ; 
but he indicates the fourth from an alveole in the young specimen pre- 
sented to the French Museum by Mr Jefferson, and he asks, whether 
this tooth had two or three denticules. In the young specimen belong- 
ing to the cabinet of our Society, there are two teeth with three denticules 
each; and anteriorly an alveole with three depressions, Plate XX. fig. 2, 
m,n,o. Was there in this alveole a tooth with three denticules, or were 
there two teeth with two denticules each, of which the anterior tooth 
having sometime previously fallen out the alveole for its anterior root 
has been obliterated ? We are inclined to believe that the latter was 
the fact. It may also be asked whether the tooth represented in Plate 
XX. fig. 1, d, corresponds with that in Plate XXI. e, in Plate XXIV. e, 
and in Plate XXV. e? We think not. Cuvier, it is true, considers 
the tooth with three denticules, in the adult jaw represented in Plate 
III. fig. 1, Grande Mastodonte,* to correspond with the posterior tooth 
with three denticules in the young jaw represented in the same plate, 
fig. .3 and 4; but the difference in the size of these two teeth, and even 
in their shape, the former being proportionably broader, is very striking. 
In all the jaws we have examined, this character is constant; thus, 
compare the tooth represented in Plate XX. d. with that in Plate XXI. e, 
Plate XXIV. e, and Plate XXV. e. It would therefore seem that 
the Mastodon has three teeth with three denticules; but to render 
this certain will require further specimens. 
The succession of the teeth in the Mastodon, takes place as follows: 
—In all the jaws the anterior teeth will be observed to be most worn. 
As the anterior teeth are worn down others are formed posterior; the 
anterior teeth successively fall out, their alveoles are obliterated, and 
* Recherches sur les Ossemens Fossiles, Tom. I. Paris, 1831. OF MASTODONS, WITH REMARKS, ETC. 
their successors advance forwards. The number of teeth which are in 
use in the young animal represented in Plate XXVI. at the same time 
seems to have been twelve, but probably at a more advanced age was 
usually not more than eight; and in old age only four. The fact of the 
jaws represented in Plates XXVIII. and XXIX. having belonged to 
adult animals is thus conclusively established, all the teeth having been 
lost, except the posterior molar in each jaw, and that has advanced 
considerably forward and is much worn. 
We subjoin the admeasurements of various teeth, appertaining to the 
lower jaw of the animals under notice. 
Tootli. 
Dimensions of Crown in inches. 
SPECIMEN. 
Length. 
Breadth. 
1. 
1.5 
1.1 
Peale’s Museum, New York, PI. XXYI. 
1.4 
1 
Academy of Natural Sciences—described in Fauna 
Americana as the Tapir Mastodontoideus. 
2. 
1.8 
1.55 
Peale’s Museum, New York, PI. XXVI. 
1.7 
1.5 
Finnel Collection, New York. 
3. 
3.1 
2.2 
Peale’s Museum, New York, PI. XXVI. 
2.9 
1.9 
Cabinet of Mr Lea. 
3.3 
2.5 
Cabinet of American Philosophical Society, PI. XX. 
3.2 
2.5 
French Museum,* figured by Cuvier. 
4. 
3.7 
2.8 
Peale’s Museum, New York, PI. XXVI. 
4.1 
2.7 
Cabinet of American Philosophical Society, PI. XX, 
3.8 
2.6 
French Museum,* figured by Cuvier. 
5. 
4.6 
3.5 
Cabinet of American Philosophical Society, PI. XXIV. 
4.5 
3.3 
Cabinet of American Philosophical Society, PI. XXV. 
5.8 
3.7 
Wistar Museum, PI. XXI. 
4.4 
3.4 
French Museum, figured by Cuvier. 
4.3 
3.2 
Philadelphia Museum. 
4.9 
3.6 
Virginia University, PI. XXVII. 
6. 
8.1 
4.3 
Wistar Museum, PI. XXI. 
6.9 
3.8 
Cabinet of American Philosophical Society. 
7.1 
3.7 
Baltimore Museum, PI. XXIII. 
7.2 
4.1 
Cabinet of American Philosophical Society, PI. XXIX. 
6 
3.4 
Cabinet of American Philosophical Society, PI.XXVIII. 
7 
3.8 
Cabinet of American Philosophical Society, PI. XXIV. 
6.5 
3.6 
Cabinet of American Philosophical Society, PI. XXV. 
7 
3.5 
French Museum, figured by Cuvier. 
7.1 
3.7 
Philadelphia Museum. 
* Same jaw. DESCRIPTIONS OF INFERIOR MAXILLARY BONES 
Before concluding it may be interesting to offer a few general re- 
marks on the animals, which are the subject of this communication, 
with a brief notice of the species hitherto described. 
For a long time the large animal whose remains are found in this 
country, was considered as the same with the Mammoth of Siberia, 
which is a true Elephant. It has been shown however by Baron 
Cuvier that they are generically different, the teeth of the latter consist- 
ing of layers of enamel penetrating the whole extent of the tooth, with 
bony matter interposed between them; whilst in the former the enamel 
forms only a covering to the bony substance, and does not penetrate it. 
From the crowns of the teeth, in the species of this genus first known 
to Cuvier, consisting of mammillaform processes, he named the genus 
Mastodon, from {Actcrros mammilla, and oS'ov; dens. 
Of this genus nine species are admitted by naturalists. Of these, 
six are indicated by Cuvier, viz. 
Species 1. M. giganteum, the well known gigantic Mastodon of 
this country. 
Species 2. M. angustidens; remains of which are found at Simorre 
in the south of France, in Germany, Tuscany, Switzerland and 
South America. Cuvier indicates the following characters as distin- 
guishing it from the M. giganteum. “Le principal et le plus gene- 
ral est que les cones de leur couronne sont sillonnees plus ou moins 
profondement, et tantot termines par plusieurs pointes, et tantot 
accompagnes d’autres cones plus petits sur leur cotes ou dans leurs 
intervalles: d’ou il resulte que la mastication produit d’abord sur cette 
couronne plusieurs petits cercles, et ensuite des trefles ou figures a trois 
lobes, mais jamais de losanges.” Recherches sur les Ossemens Fossiles, 
Tom. I. p. 254. These differences will be at once perceived on com- 
paring the partially worn tooth of the M. giganteum, Plate XXI., and 
Plate XXIV. e, with the teeth of the M. angustidens represented in 
Cuvier’s Ossemens Fossiles, Divers Mastodontes, Plate I. fig. 4, and 
Plate III. fig. 2 and 4. 
Species 3. M. Cordillerarum. This species is founded on a tooth 
discovered near the volcano of Imbaburra, in the kingdom of Quito, 
and two teeth from the province of Chiquitos, near St Crux de la 
Sierra. The tubercles of these teeth are divided like those of the angus- OF MASTODONS, WITH REMARKS, ETC. 
Helens, whilst their proportions are the same as those of the giganteum 
with three denticules, but they are distinguished by the figure (trifle) 
formed by the enamel in the partially worn tooth, being different from 
the lozenge in the M. giganteum. See Cuvier’s Ossemens Fossiles, 
Divers Mastodontes, PI. II. fig. 1. 
Species 4. M. Humboldtii. This species is founded on a tooth ob- 
tained by M. Humboldt at Conception du Chili. This tooth is nearly 
square, and smaller than the preceding. See Cuvier’s Ossemens Fos- 
siles. Divers Mastodontes, PI. II. fig. 5. 
Species 5. M. parvus, founded on a tooth discovered in Europe, 
and which M. Cuvier thinks too small to be referred to any of the 
preceding species. It is represented in the Ossemens Fossiles, Divers 
Mastodontes, PI. II. fig. 11. 
Species 6. M. Tapyroides. This is founded on a tooth obtained at 
Montabusard, near Orleans. Its crown, simply indented, is not so ex- 
actly divided into two points, as those of the preceding species, which 
has led Cuvier to suspect that it may belong to a different species. It 
is figured in the Ossemens Fossiles, Divers Mastodontes, Pl. III. fig. 6. 
Species 7. M. Arvernensis. This species was founded by M.M. 
Croizet and Jobert, Sen., upon a fragment of an upper jaw, a humerus, 
&c. found in the department of the Puy de Dome, in France.* A 
portion of the left side of the upper jaw and some separate teeth have 
since been found at Eppelsheim, not far from Alzei, in the grand 
duchy of Hessen, and are now in the museum at Darmstadt, f 
Species 8. M. latidens. This species and the following are de- 
scribed by Mr Clift, in the second volume of the Transactions of the 
Geological Society of London, second series. They are founded upon 
some remains collected by Mr Crawford along the course of the river 
Irawadi, between Rangoon and Ava, in Asia. The teeth in the M. 
latulens consist of “seven denticules, which are elevated, rounded, and 
mammillated, the mammillae being from three to four in number.” 
See Plate XXXVIII., Trans. Geolog. Soc. Lond. Vol. 2, New Series. 
* Recherches sur les Ossemens Fossiles du Departement du Puy de Dome; par l’Abbe 
Croizet et Jobert, aine. Paris, 4to, avee un atlas des Planches. 
t Ueber Mastodon arvernensis bei Eppelsheim. Von Herm. v. Meyer, M. d. A. d. N. 
(Bei der Akademie eingegangen den 24 Juli, 1829.) Acta Acad. Caes. Leop. Carol. Nat. 
Cur. Vol. XV. Part II. DESCRIPTIONS OF INFERIOR MAXILLARY BONES 
Species 9. M. elephantoides. Distinguished by the teeth being 
smaller, the denticules more compressed and closer together, and the 
enamel thinner than in the preceding species. The denticules form a 
series of plates, mucronate with small points. There is no apparent 
commissure, nor any central depression, on the contrary, the plates rise 
in the middle. The teeth have ten denticules, with from five to eight 
mammillae. See Geological Transactions of London, Yol. II. Second 
Series, PL XXXVIII. 
Mr Meyer, in his account of the remains of the Mastodon Jlrvernen- 
sis, found at Eppelsheim, alludes to another species, the M. turicensis, 
as occurring in the brown coal of the molass formation of Switzerland; 
but by whom this species has been described, or what are its charac- 
ters, we have been unable to discover. 
In the third volume of the Memorie della Reale Jlccademia delle Sci- 
enze di Torino, professor Borson has described a tooth, found at Villanova 
d’Astica, in Piedmont, and which he ascribes to the giganteum. After 
a careful examination of the description and drawing, in the work 
referred to, and of a cast of the tooth, in the Cabinet of the Academy of 
Natural Sciences of this city, we feel persuaded that it does not apper- 
tain to that species, the denticules having no longitudinal commissure. 
It probably belongs to a new species, and we would suggest the propriety 
of dedicating it to professor Borson, under the name of M. Borsoni. 
If the differences presented by the specimens we have describ- 
ed, be considered as sufficient to indicate a difference in species, or 
should future researches confirm my suspicions on this subject, four 
new species will be added to our Fauna; and we wTould dedicate the 
first to Baron Cuvier, (M. Cuvieri, PI. XXIV.) to whom science is under 
such immense obligations; the second to Mr Jefferson, (M. Jeffersoni, 
PL XXY.) to whom the Society is indebted for the valuable specimens 
of this animal in their cabinet; the third to our vice-president, Mr Z. 
Collins, ( TCollinsii, Pl. XXVIII.) one of the most zealous naturalists 
of whom this country can boast; and the fourth to our lamented God- 
man (T. Godmani. Pl. XXIX.). 
In the Finnel collection there are several jaws, differing in many 
respects from any we have described. There are the portions of two 
inferior maxillary bones belonging to the left side, flattened superiorly, 
and their rami exceedingly thick. They contain one tooth each, with OF MASTODONS, WITH REMARKS, ETC. 
five denticules, the tooth situated towards the inner side of the thick 
ramus. There is also in the same collection, a fragment of the ante- 
rior portion of a lower jaw, with the chin rostrated somewhat, like 
that of the Tetracaulodon, but more expanded, and without alveoli. 
It conveyed the idea to some of the naturalists who had examined it, 
of its being the adolescent state of the animal described by Dr God- 
man, the tusks having fallen out, and their alveoli being just obliter- 
ated. We cannot, however, consider such a view as the correct one; 
the fact shown by our specimens, that the tusks exist in all ages of 
the animal, is a sufficient disproval of it. 
I must not close this communication without expressing the obli- 
gations I am under to various gentlemen, for the liberality with 
which they have facilitated my investigations, and even placed at my 
disposal such specimens as I wished to collect together for the pur- 
pose of minute comparison. 
To the liberality of the trustees of the Baltimore Museum, I am indebt- 
ed for the use of the splendid jaw of the M. giganteum, belonging to that 
collection. J. P. Wetherill, Esq., with his characteristic liberality, has 
also placed at my disposal his valuable collection, deposited in the cabinet 
of the Academy of Natural Sciences, and the most interesting specimens 
belonging to which are submitted to the inspection of the members. 
Mr Rubens Peale, the proprietor of the remains of the animal described 
by Dr Godman, has also placed at my disposition those remains, and 
the inferior maxillary is now in the cabinet of the Society. To the 
trustees of the University of Pennsylvania and Dr Horner, I am in- 
debted for the opportunity of figuring and describing a very fine frag- 
ment of a lower jaw belonging to the Wistar Museum.* The pro- 
prietors of the magnificent collection of bones, recently disinterred at 
Big-bone Lick, by captain Finnel, and now exhibiting at New York, 
liberally afforded me the greatest facilities in examining that collection, 
and even allowed me the loan of a highly interesting tooth belonging 
to it.f 
* The trustees of the University of Pennsylvania subsequently allowed this jaw to be 
deposited, for several months, in the cabinet of the Philosophical Society. 
t In this collection there are portions of fourteen inferior maxillary bones of the Mastodon, 
about one hundred teeth, some enormous tusks, and the most perfect cranium that has ever 
yet been discovered. DESCRIPTIONS OF INFERIOR MAXILLARY BONES 
To William Cooper, Esq., of New York, I am indebted for the oppor- 
tunity of examining the valuable collection of Mastodon bones, in the 
cabinet of the Lyceum of Natural History of that city; and still fur- 
ther, for having communicated to me some highly interesting speci- 
mens belonging to his private cabinet. This liberality will be at once 
appreciated by the naturalist, when it is stated, that Mr Cooper has 
himself been long engaged in the investigation of the history of the 
Mastodon ;* that he has visited Big-bone Lick, for the purpose of ob- 
taining materials; and that upwards of a year since, he communicated 
to the Lyceum of Natural History, New York, some observations on 
the dentition of that animal.f 
We have reason, further to hope, through the exertion of our friend, 
Professor Patterson, of the University of Virginia, to be able to exhibit 
to the Society, the lower jaw belonging to the museum of that univer- 
sity, noticed by Dr Godman; and also, to present a description and 
drawing of that bone. 
It may be allowable here to add, that great confidence may be placed 
in the accuracy of the drawings, which accompany this paper, and 
which were all taken with the aid of a camera lucida, by Mr Dray- 
ton, yvhose skill and accuracy in his art, the Transactions of the Society 
bear ample evidence. 
Since I had the honour of submitting to the Society, in May last, the 
preceding communication, I have been favoured by the liberality of 
the visiters of the University of Virginia, with the loan of the inferior 
maxillary bone of the Tetracaulodon, alluded to by the late Dr God- 
man in his memoir, published in the third volume, page 478, of our 
* The Society may expect to receive from Mr Cooper some of the results of these re- 
searches, and we have no doubt that he will supply many of the deficiencies in this memoir. 
He will also probably describe many bones of the Mastodon, which it would have taken us 
too far from our main purpose (which was to refute the belief, that Dr Godman’s animal was 
only the young of the gigantic Mastodon) to describe. 
t These have not been published, the author being unable to satisfy himself in relation to 
some points, which we have been so fortunate as to establish from the specimens in the 
cabinet of our Society. OF MASTODONS, WITH REMARKS, ETC. 
Transactions; and I have now the gratification of exhibiting it to the 
Society, and of presenting to them the accompanying description and 
drawings. 
This specimen consists of the right half of the lower jaw, two teeth, 
the chin, and a portion of one tusk, with the socket for the other. Its 
length is feet three inches; height, from the base of the ramus to 
the upper edge of the alveolar process, six inches. 
In general form, this bone corresponds in the most marked manner 
with two of the specimens belonging to the Society, and one of which 
is represented in Plate XXVIII. The muscular impressions and tuber- 
osities, at the outer and posterior portion of the jaw, are, however, less 
strongly marked in the former as was to be expected from the 
difference in age of the animals. It will he also observed, that the 
anterior and upper edge of the coronoid process projects forward in 
the latter; but it must be recollected, that that part is mutilated in 
the jaw represented in Plate XXVIII. 
The condyloid process is deficient, and the upper edge of the semi- 
lunar notch and of the coronoid process is slightly mutilated. 
The posterior tooth is contained in a bony cavity, at the base of the 
coronoid process, but is visible at the inner aspect of the jaw. It has 
eight points and a large talon; it is impossible, from its position in the 
jaw~, to obtain correctly its admeasurements. 
Anterior to this tooth is another, possessing six points, slightly worn; 
it is four inches and nine-tenths long, and three inches six-tenths wide. 
Portions of the sockets for the two teeth immediately preceding this 
still remain, but, unfortunately, the teeth are lost. Had they been still 
in the jaw, it would have enabled us to settle the point respecting the 
number of teeth possessed by the animal. 
The anterior surface of the chin is slightly mutilated. The plate of 
bone, forming the base of the sockets for the tusks, is deficient. The 
left alveolus is empty, the right contains a fragment of a tusk. This 
tusk extends, anteriorly, but slightly beyond the chin; it projects some- 
what inwardly, apparently driven in by violence; its anterior extrem- 
ity is smooth; its base is cup-shaped. 
The accompanying drawings are so accurate as to render further 
description unnecessary. DESCRIPTIONS OF INFERIOR MAXILLARY BONES 
EXPLANATION OF THE PLATES. 
AU the figures are one-fourth the natural size. 
Plate XX. Two views of a fragment of the lower jaw, left side, of a young Mastodon, in 
the cabinet of the American Philosophical Society. 
Fig. 1. External view. Fig. 2. Superior view. 
m. n. o. Alveoli from which the teeth have fallen out. 
c. Molar, with three denticules. 
d. Molar, with three denticules. 
r. Mental foramen for nerve and blood-vessel. 
Plate XXI. Three views of a fragment of the lower jaw, left side, of an adolescent Masto- 
don, in the Wistar Museum, University of Pennsylvania. 
Fig. 1. Exterior view. Fig. 2. Superior view. Fig. 3. Interior view. 
f. Posterior molar, with five denticules and a heel. 
e. Penultimate molar, with three denticules. 
Plate XXII. Fig. 1 and 2. Two views of a small fragment of the lower jaw, right side, of 
a Mastodon, in the cabinet of the American Philosophical Society. 
Fig. 3 and 4. Two views of a molar tooth, upper jaw, of a Mastodon, in the cabinet of the 
American Philosophical Society. This tooth appears to differ from any hitherto described. 
It resembles the teeth represented in Cuvier, (Ossemens Fossiles, Plate IV. fig. 1, 3, 4, and 6, 
Divers Mastodontes) in the enamel being crenulated; but it differs from them in the arrangement 
of the enamel. It is probably an undescribed species, and we propose to dedicate it to our 
estimable friend, the distinguished professor of the institutes and practice of medicine in the 
University of Pennsylvania, and Vice-President of this Society, Dr Chapman. 
Plate XXlII. Two views of a portion of the lower jaw, right side, of the Mastodon gigan- 
team, in the Baltimore Museum. 
f. Posterior molar. 
p. q. Anterior mental foramina. 
s. Foliated expansion of the chin. 
x. Depression in the articulating surface of the condyloid process. 
y. Foramen for the passage of the inferior maxillary nerve, and artery to the teeth. 
Plate XXIV. Two views of a fragment of the lower jaw, right side, of a Mastodon, in the 
cabinet of the American Philosophical Society. 
/. Posterior molar, with four points and a broad heel. 
e. Penultimate molar, with three points. OF MASTODONS, WITH REMARKS, ETC. 
Plate XXV. Two views of a fragment of a lower jaw, right side, of a Mastodon, in the 
cabinet of the American Philosophical Society. 
f. Posterior molar, with four points and a broad heel. 
e. Penultimate molar, with three points. 
Plate XXVI, Fig. 1 and 2. Two views of the fragment of a lower jaw of a young Te- 
tracaulodon, in Peale’s Museum, New York, described by Dr Godman, in Vol. III. N. S. of 
the Transactions of the American Philosophical Society. 
a. Anterior milk molar, with two dentieules. 
h. Second milk molar, with two dentieules, and a small process. 
c. Third milk molar, with three dentieules. 
The tusk belonging to this jaw is accurately represented in Plate XVIII. fig. 2, in Vol. III. 
N. S. of these Transactions, 
Fig. 3. Tusk of an adult Tetracaulodon, in the cabinet of the Academy of Natural Sciences 
of Philadelphia, deposited by J. P. Wetherill, Esq. 
Plate XXVII. Three views of a portion of a lower jaw, right side, of an adolescent Tetra- 
caulodon, in the Museum of the University of Virginia, and to which allusion is made by Dr 
Godman, in his memoir in the preceding volume of these Transactions. 
/. Posterior molar, with four dentieules and a heel. 
e. Penultimate molar, with three points. 
Plate XXVIII. Two views of a portion of the lower jaw, right side, of an adult Tetracau- 
lodon in the cabinet of the American Philosophical Society. 
f. Posterior molar with four points. 
p. q. Mental foramina. 
r. Radiated muscular impressions. 
t. t. Tubercles, where the muscle was inserted, 
v. Inner point of second denticule. 
The socket for the tusk could not be exhibited, but its situation is shown by the dotted line 
representing a tusk. 
Plate XXIX. Two views of a fragment of a lower jaw, right side, of an adult Tetracaulo- 
don, in the cabinet of the American Philosophical Society. 
x. Excavation between the coronoid process and posterior molar. 
f. Posterior molar, with four points and a heel. 
z. Socket for tusk. 
Philadelphia, December 2, 1831. Note.—The Society have had casts taken from the bones repre- 
sented in the accompanying plates; and sets of them may be obtained. PL. XX 
fig. 2. 
Fig.]. 
Mastodon (young) 
Cabine t Am . Philos. Soc. PI.. XXI. 
lit}. 3. 
Fig. 2. 
Fig.l. 
Mastodon (adolescent) 
distal’ Musetun. PL. XXII. 
Tig. 2 
Fig 4 
Fig. 3. 
Fig l 
Mastodon ( adult) 
('abined Jm. Thilos. Soc. 1\I ..XXIII. 
Fig. ?. 
Fiv/l. 
Mastodon giganteum (adult) 
Baltimore Museum. i’l.xxiy: 
Fiy.2. 
Fyl- 
Masto don (Cuvieri ) 
Cabinet Am.Fhzlos.Soc. PL . XXV. 
Fig.2. 
Fig.l 
Mastodon CTeffersonii.) 
Cabinet A7n.Ti1ilvs.S0c. PL.XXVI. 
%. c?. 
I’ig.2. 
I'ig.L 
Tetracaxilodon (youngj 
Peak* Museum Mew York. PL. XXVII. 
%• 
luf. 2. 
■Rff.l. 
Tetracaulodon (Adolescent ) 
Cabinet University of Vir. pl . ixvm. 
Fiq. 2. 
Fief.]. 
Tetrac anlo doTX ( Collinsii ) 
Cabinet Pm. Philos Sac. PL .XXIX. 
Fig. 2. 
Ficfl. 
TetracauI odon (Godmard) 
Cabinet Am.Philos Soc.