CUVIERIAN CLASSIFICATION 
OF 
ANIMATED UST ATTRE. 
BY J. H. McQUILLEN, M.D., D.D.S., 
m - ■ 
PROFESSOR OF ANATOMY, PHYSIOLOGY, AND HYGIENE IN THE PHILADELPHIA DENTAL COLLEGE; LATE PRESIDENT 
OF THE AMERICAN DENTAL ASSOCIATION; CORRESPONDING SECRETARY OF THE ODONTOGRAPHIC 
SOCIETY OF PENNSYLVANIA; MEMBER OF THE ACADEMY OF NATURAL SCIENCES, 
PHILADELPHIA, ODONTOLOGICAL SOCIETY OF GREAT BRITAIN, ETC. 
An address delivered before the Central Massachusetts Dental Association, 
Worcester, Mass., May 1, 1866. 
Ladies and Gentlemen:-Fully recognizing the difficulties that en- 
viron the presentation of a scientific subject to an audience composed of 
professional and non-professional persons, of succeeding in interesting 
and instructing the latter, and at the same time satisfying the former, is 
indeed a difficult, if not an impossible task; to secure and maintain the 
attention of those entirely unfamiliar with the subject, one must generalize 
to a great extent, and particularly avoid the extended details and the use 
(to a certain degree) of scientific nomenclature, which would be proper 
before a body of strictly professional men; influenced by considerations 
such as these, in directing attention to the subject-matter of the evening, 
in the brief time allotted, I shall, of necessity, be compelled to treat it in 
the most general manner, but it is hoped in a sufficiently suggestive and 
interesting way to awaken a desire on the part of some present to enter 
upon the study of natural history. If this end should be accomplished, 
the effort will not have been futile. Man must have his pleasures in 
this world, and it is far better that those pleasures should lie above rather 
than below the diaphragm, that they should be of a character to ad- 
vance and elevate rather than to debase and degrade him. Socrates 
said to his disciples that the most forcible and truthful axiom he had 
ever met with, was that inscribed upon the temple of Delphus-"Know 
thyself." What nobler or more interesting study can there be than that 
of man viewed morally, mentally, and physically ? To thoroughly under- 
stand man, however, and his place in nature, it is necessary to examine 
his surroundings of the inorganic and organic world, that we may prop- 
erly appreciate whence he comes, and whither he goes. Fortunately for 
us, owing to the efforts of such master-minds as Linnaeus, Cuvier, Owen, 
Agassiz and others, the organic world has been classified in such an orderly 
and methodical manner that its study is far more easy than it was prior to 2 
their time. To Cuvier in particular, the comparative anatomist and the 
world at large is under lasting obligations, for although in some slight par- 
ticulars his classification of animated nature has been modified, the accu- 
racy of the plan, as a whole, is made manifest by its universal adoption on 
the part of naturalists. The knowledge which we possess of the structure 
and habits of many animals, however, is exceedingly imperfect, and ample 
opportunities are afforded for those whose tastes lead them in such direc- 
tions to contribute fro the general stock of information, and as an incen- 
tive to exertion, it may be stated that new species are being constantly 
discovered by those who devote themselves to such pursuits. We esteem 
it a privilege, and eminently improving, to make ourselves familiar with 
the thoughts of the leading minds of this world, who, like ourselves, are 
erring and fallible men; but how much more elevating and liberalizing is 
the study of the works of One who is infallible, and manifests boundless 
wisdom and beneficence in all his works I 
Prior to the consideration of the classification of animated nature, it 
will be advisable to refer briefly to the differences between inorganic 
and organic matter,-minerals being arranged under the head of the in- 
organic, vegetables and animals under the organic. In the inorganic there 
are no organs for the performance of specific functions, and no such thing 
as birth, life, or death ; in the organic, on the other hand, all of these 
prevail, and organized bodies being derived from similar ones, the neces- 
sity for parents seems to be invariably manifest; and the axiom of Harvey, 
"omne vivum ex ovof from a seed or egg every living thing arises, ap- 
pears to prevail throughout. The theory of spontaneous generation, 
which supposes that living objects may arise by the conjunction of the ele- 
ments of decaying animal or vegetable matter, has been subjected of late 
to the most rigid examination, and apparently becomes more and more 
improbable the closer it is investigated. 
In form, size, chemical composition, preservation, and duration, the con- 
trast is most striking between the inorganic and organic. Inorganic 
matters are aeriform, liquid, or solid, and are prone to assume the crystal- 
line form, and the smallest particle of chalk is the same in structure and 
composition as the largest chalk cliffs on the sea-coast. These may exist 
apparently unchanged for ages. Organic bodies, on the contrary, con- 
sist of an assemblage of organs, each body has a definite form and size 
peculiar to its species, by which it is distinguished from all others, and 
the evidence of incessant change in them is readily observable. Inorganic 
bodies, by chemical analysis, may be resolved into about sixty-five simple 
substances or elements, that is to say, which have hitherto resisted decom- 
position on the part of the chemist. These elements unite in certain defi- 
nite proportions to form the compound inorganic substances which sur- 
round us on all sides. Of these sixty-five simple elements, only about 
seventeen enter into the composition of organic bodies, vegetable or 
animal. 3 
The preservation of the individual makes it necessary that organized 
bodies should be supplied with food. This the plant obtains by absorbing 
to itself inorganic matters, such as carbonic acid, water, ammonia, and the 
earthy salts, from the surrounding atmosphere and soil, and animals feeding 
upon vegetables and upon each other secure materials sufficient to supply 
the waste which is constantly going on in their organisms. It is not only 
necessary to attend to the preservation of the individual, but the perpetuity 
of the species is equally important, and this is secured by the union of the 
sexes. The duration of the individual is limited ; in other words, it has a 
definite period of existence, divisible into ages, at the termination of which 
death invariably ensues, and the material which entered into the composition 
of the vegetable or animal is returned to the earth and atmosphere, from 
which it was originally obtained, to be again resolved into the simple 
elements. Even during life, however, this constant interchange between 
the inorganic and organic is taking place; in every act of respiration, 
oxygen is obtained from the atmosphere in inspiration, and carbonic acid 
gas given off to it in expiration ; the food that is taken into the body, 
vegetable or animal, is only so much matter which was originally obtained 
from the inorganic world, and after subserving the purposes of the econ- 
omy, is again returned to the source whence it came in the different ex- 
cretions of the body. Constant change is thus taking place, not only 
in the organic, but also in the inorganic world, the former absorbing ma- 
terials from the latter at one time, to be replaced at another. The ele- 
ments which enter into the composition of our body indeed are only bor- 
rowed from the earth and surrounding atmosphere, and united together 
by the operation of the natural forces, and then, after a brief period, this 
relation is dissolved, and the constituent elements separate, to again enter 
into new combinations. This constant absorption from and return of ma- 
terials to the earth and atmosphere by organized beings keeps up the con- 
tinuous stream of life, and renders the source inexhaustible. The Rev. 
Mr. Malthus, an eminent mathematician, demonstrated years ago, by a 
most minute and accurate calculation, tfiat if there was not constant death 
as well as birth, organic beings, increasing under such circumstances, in 
a geometrical ratio-and as the means of existence cannot be made to in- 
crease in the same ratio-a condition of affairs eventually would be reached 
when there would be neither food nor space on the globe sufficient to ac- 
commodate the necessities of vegetables and animals. The constant inter- 
change between the organic and inorganic, in the dying out of the old, not 
only affords place for the new, but also gives to the face of nature the 
freshness and vitality which are so pleasing to our senses and so invigora- 
ting to our physical and mental powers. The fossil remains in the geo- 
logical strata indicate most conclusively that ages upon ages long before 
the world was habited by man, or was a fit place of habitation for him, 
death prevailed among vegetables and animals. In this record, the 4 
grave-yard of past ages, is exhibited in chronological order one of the 
most beautiful evidences of the harmony of nature's laws, and the wonder- 
ful system and wisdom of God: first creating the lower forms of organic 
life, and then in different geological ages, through successive stages of 
advancement, one class of animals after another appearing, until eventu- 
ally the world is prepared for the maintenance of man. Thus, in the 
primary or palaeozoic age, fishes were the masters of creation; in the 
secondary age air-breathing animals first appeared, the reptiles pre- 
dominating over other animals; in the tertiary age, terrestrial mam- 
mals of great size present themselves; while it is not until the modern 
age that the reign of man begins. In the Testimony of the Rocks, 
by Hugh Miller, and in the Religion of Geology, by the Rev. Dr. 
Edward Hitchcock, President of Amherst College, are embodied con- 
clusive arguments in substantiation of the statements relative to fossil 
remains. The facts presented indicate most clearly that the matter which 
entered into the composition of animals and vegetables in the earliest 
period of the world is still in existence; and that we are formed of mate- 
rials as old as the creation, which have served the purposes of beings an- 
terior to and during our own time, as we, in turn, by constant disinte- 
gration of our tissues, yield up the matter of which we are composed, to 
furnish material for new existences. What we call death or destruction 
is not therefore annihilation, but change, for there is no such thing as the 
annihilation of matter or of force; either may disappear from our view, 
but they are not destroyed, they are only changed in form, and will reap- 
pear in some other shape. In illustration of this, Bryant, America's 
great poet of nature, has forcibly said : 
"Go forth, under the open sky, and list 
To nature's teachings, while from all around 
Earth and her waters, and the depths of air, 
Comes a still voice. Yet a few days, and thee 
The all-beholding sun shall see no more 
In all his course; nor yet in the cold ground, 
Where thy pale form was laid, with many tears, 
Nor in the embrace of ocean, shall exist 
Thy image. Earth, that nourished thee, shall claim 
Thy growth, to be resolved to earth again, 
And, lost each human trace, surrendering up 
Thine individual being, shalt thou go 
To mix forever with the elements, 
To be a brother to the insensible rock 
And to the sluggish clod which the rude swain 
Turns with his share, and treads upon. The oak 
Shall send his roots abroad, and pierce thy mould." 
To some persons, the idea that the materials that enter into the com- 
position of their bodies is to be thus used may carry with it rather un- 
pleasant associations. To a sentient being, however, who, in his day and 5 
generation does everything in his power to ameliorate the sufferings, 
contribute to the happiness, and elevate the condition of his fellow-man; 
who recognizes that, while made in the spiritual image of God, he has 
a material body like that of other animals, which is but a dwelling-place 
for the spirit during a brief period, and when the tenement becomes unfit 
for it as a place of habitation, returns to the source whence it came, there 
is something delightful in the consciousness that even the materials which 
form part of his organism are not to be wasted, but, on the contrary, will 
be employed for some useful purpose, perchance to become part and parcel 
of a noble oak, that shall please the eye, and shelter from the storm or the 
heat of the sun a fellow-being; or enter into the composition of a beauti- 
ful flower, whose fragrance shall impart to the surrounding air an aroma 
grateful and exhilarating to all. 
Having directed attention in a general way to the characteristic differ- 
ences between inorganic and organic matter, the dependence of the latter 
on the former, and the constant interchange which takes place between 
them, the way is opened to more properly appreciate the classification of 
animated nature. 
In every department of science, classification has two prominent pur- 
poses to subserve : first, to organize the knowledge which has been gained 
through the exertions of innumerable investigators by having it arranged 
in a methodical manner so as to render its acquisition, retention, and use 
most easy and successful; second, that it may be employed to facilitate 
identification, or the recognition of the resemblances or differences exist- 
ing between facts or objects embraced in the line of study, and in that way 
enable observers who are familiar with the great principles underlying 
science and their special applications to confirm or disprove mooted points, 
or by the discovery of new objects or new principles to add to the general 
stock of knowledge. The importance and advantage of a regular and sys- 
tematic arrangement of science are never more apparent than when men of 
fair perceptions, respectable abilities, and liberal attainments, but who 
lack the essential quality of an orderly arrangement of the knowledge 
they have acquired, attempt to present their views either as speakers or 
writers; for in place of offering them in a clear, connected, and compre- 
hensive manner that would secure attention and benefit listeners or readers, 
they are presented in such a disjointed and incoherent way that the use- 
fulness and efficiency of their efforts are greatly impaired. Were it not 
that in all ages the master-spirits of science, those broad, generalizing, and 
philosophical minds, who, in addition to patient, laborious investigation 
on their own part, taking advantage of the recorded facts of reliable ob- 
servers, have always endeavored to discover the great cardinal principles 
upon which science rests, and by demonstrating the existence of certain 
fixed laws have in this way simplified its study by arranging a number of 
apparently isolated facts or objects in well-defined groups, it would be im- 6 
possible at the present day for any mind, however vast the power or re- 
markable the memory, to grasp, retain, or successfully manage such heter- 
ogeneous masses of material as would exist without classification. As 
Sir John Herschel has said, " Science is the knowledge of many, or- 
derly and methodically arranged and digested, so as to become attain- 
able by one." To no department does this apply with more force than to 
Natural History, and from the time of its founder, Aristotle, naturalists, 
by a careful study of the resemblances and differences presented by ani- 
mals, have endeavored to arrange them into well-defined groups, bringing 
together those which have certain marked resemblances, and separating 
these from others that are dissimilar to them. 
In many respects, the observations and suggestions of the Greek philos- 
opher in relation to animated nature have not been improved upon during 
two thousand years, but in one most important particular he made a very 
great mistake. Supposing that a differential characteristic existed in the 
presence or absence of blood, and regarding as such only that fluid which 
has a red color, in his first division of animals, Aristotle classified them 
in two primary groups, as enaima, sanguineous, or possessing blood, and 
anaima, exsanguineous, or without blood. This arrangement prevailed 
for a long time, but eventually, when it was found that many of the latter 
group possessed blood, although of a different color, his divisions were still 
retained, but spoken of as those with "red blood" and those with "white 
blood." In the minute and careful dissections of the lower animals by 
Cuvier, he discovered red blood in some of the worms which had heretofore 
been regarded as only possessing white blood; this demonstrated the utter 
fallacy of the distinction just referred to. Lamarck then observing that 
certain animals possessed a vertebral column (the backbone of common 
parlance), which is entirely absent in a far greater number, proposed to 
classify them as the Vertebrata and Invertebrata. This classification 
is still employed by naturalists as a matter of convenience, but the recog- 
nition of the fact that while the first group is based upon the possession 
of a positive characteristic, the other is due to a negation, lessened its value, 
and particularly after the important discovery that the vertebral column 
is subordinate to a higher office than merely serving as a central axis to 
the skeleton, viz.: affording lodgment and protection to that important 
and delicate nervous mass, the spinal cord, while its expanded portion, 
the brain, is safely lodged in the skull. This led Cuvier to investigate 
the nervous system of the invertebrata, and discovering, as the result of 
elaborate dissections, important modifications of that system in them, he 
established the four "Great Divisions" or "Sub-Kingdoms" of the 
Animal Kingdom, which are so well known, have contributed so much to 
facilitate the study of Natural History, and immortalize his name. His 
" Great Divisions" are divisible into "classes," these again into smaller 
groups named "orders," orders into "families," families into "gen- 
era," and the latter into "species." 7 
Aristotle had used genera and species to distinguish between 
larger and smaller groups; and Linnaus, who did much to systemize 
the study of animals, added to these classes and orders; but all these 
terms were employed by him in a manner that frequently induced great 
confusion, and it was not until the promulgation of Cuvier's plan that 
the classification of animated nature could be said to have a firm and re- 
liable basis. A general idea of his system may be gained by reference to 
the diagram on the blackboard, which I have arranged so as to offer in a 
tabular or skeleton form his plan, with the modifications that appear to 
me to adapt it-at least to a certain degree-to the present condition of 
Zoology; it presents in particular that portion of the Animal Kingdom, 
the vertebrata, with which you are most familiar. 
KINGDOMS. 
Mineral. Vegetable. Animal. 
ARCHETYPES. 
Vertebrata. Articulata. Mollusca. Radiata, 
CLASSES. 
Pisces. Reptilia. Amphibia. Aves. Mammalia. 
Sur-Classes. 
1 VlVIPARA, 
OR 
Placentalia 
Bimana. Quadrumana. Cheiroptera. 
Insectivora. Carnivora. Cetacea. 
Ropentia. Edentata. 
Pachydermata. Ruminantia. 
"ORDERS.- 
Unguiculata. 
[ Ungulata. 
2. OVOVIVIPARA. 
OR 
Implacentalia. 
Marsupiata. 
FAMILIES. 
GENERA. 
SPECIES. 
Monotremata. 
In the construction of his classification, Cuvier was largely indebted 
to the labors of naturalists who had preceded or were contemporary with 
him,* and it has undergone and must continue to undergo modifications 
* In the preface to the first edition of Cuvier's great work, The Animal King- 
dom, he says: "Had I been constrained to depend upon myself alone, I should not 
have been able to prepare even the simple sketch I now give; but the resources of 
my position seemed to me to supply what I wanted both of time and talent. Living 
in the midst of so many able naturalists, drawing from their works as fast as they 
appeared, enjoying the use of their collections as freely as themselves, and having 
formed a very considerable one myself, especially appropriated to my object, a great 
portion of my labor consisted merely in the employment of so many rich materials." 8 
and improvements on the part of subsequent observers. It is based 
upon the recognition of a unity of plan or conformation of structure 
among beings apparently dissimilar to each other. In the arrangement 
of the different groups advantage is taken of certain general plans of 
organization observable in animals ; the adaptation of their bodies for 
swimming in the water, creeping or walking on the land, or flying in the 
air; the structure and peculiarities of their limbs; the form and struc- 
ture of their teeth, or the absence of the latter, etc. To properly under- 
stand the classification it is necessary to take up the different groups in 
regular order. In describing them, a number of technical terms of neces- 
sity will have to be employed. These, however, will be carefully defined, 
so that persons least familiar with them may understand their mean- 
ing; in this connection it may not be amiss to state that the objections 
urged against the use of Greek and Latin terms in scientific nomenclature 
are not well founded. The aim is not to mystify, but rather to simplify 
science by their use; for in the employment of universal languages such 
as Greek and Latin, a single name applied to a given object will answer 
better the purpose, and be far more easy of remembrance, than to be 
compelled to memorize half a dozen names in as many different lan- 
guages. That which the masters of science have seen fit to use, you may 
rest assured is right. Commencing with 
KINGDOMS. 
Minerals, Vegetables, and Animals are arranged under this head. 
Having already stated that these are divisible into the inorganic and 
organic, it is only necessary to consider the characteristic resemblances 
and differences between animals and vegetables. They agree in origi- 
nating from parents in an egg or seed, and in the fact that the various 
structures which enter into their composition commence in a cell, and in 
the integrity of the organism during life, vegetable or animal, being main- 
tained through the continuous operation of millions of these cells. In 
these is found that itni7y of organization which naturalists had been 
dreaming of and philosophizing about for ages, but which was left for 
Schleiden, Schwann, and Von Baer to discover and demonstrate in 
our own day. 
They also resemble each other in the possession on the part of each of 
the organic or nutritive and the reproductive functions, viz.: Digestion, 
Absorption, Respiration, Circulation, Nutrition, Secretion, Calorifica- 
tion, and Generation. In addition to these, animals possess Sensation 
and Voluntary Motion, functions which are not enjoyed by the Vegetable. 
The latter, fixed to the soil, is enabled to derive from it and the surround- 
ing atmosphere materials inservient to its nutrition; and although some 
of the lower forms of animals are fixed to one spot during their entire 
life, and give little evidence of the possession of sensation or voluntary 9 
motion, and lead an almost vegetative existence, the vast majority pos- 
sessing the means of locomotion, and a central organ or stomach for the 
reception and digestion of food, are compelled to pass from one place to 
another in search of it. The well-defined differences, readily recognizable 
by the most ordinary observer in the higher forms of vegetables or ani- 
mals, renders it very easy to distinguish one from the other, but the 
lowest types of each require the exercise of great care on the part of 
naturalists to decide which they belong to. As an illustration of this, 
the sponge at one time was regarded as a vegetable, while it is now 
fully recognized as belonging to the Animal Kingdom. The simplest 
means of demonstrating whether a certain structure has a vegetable or 
animal origin is to burn it; under such circumstances, the latter invariably 
gives off a peculiar and unmistakable odor sufficient to decide the point 
beyond a question of doubt. 
ARCHETYPES. 
The primary divisions of the Animal Kingdom have been denominated 
Sub-Kingdoms, Departments, etc.; but I prefer to employ, in place of 
any of these, Archetypes, on account of the fact that the hundreds of 
thousands of species have been arranged, as the Vertebrata, Articu- 
lata, Mollusca, or Radiata, according to four general plans of con- 
struction observable in them. The last-named, however, is regarded by 
many naturalists as being defective, and another sub-kingdom, the Pro- 
tozoa, is now generally agreed upon, and the propriety of recognizing 
two or more in addition to this is strongly urged by eminent observers. 
The Vertebrata (Lat. vertere, to turn) are so named on account 
of the presence of the vertebral column, which at its upper extremity 
is expanded into the skull, and terminating in animals in a tail, con- 
sists of a series of bones, so arranged as to give flexibility of motion, 
serve as a central axis for the rest of the skeleton (which is internal), and 
afford, as already stated, lodgment and protection for the spinal cord, 
while the brain is safely lodged in the skull. Connected with the sides of 
the vertebrae are a series of ribs, which are generally united in front with 
the sternum, or breast-bone, thus forming a cavity which affords protec- 
tion to the organs of respiration and circulation ; in addition to the ribs, 
two or four extremities are usually appended for purposes of locomo- 
tion. The bones are united by ligaments, and moved by muscles, which 
pass from one bone to another. All of these animals have red blood, 
with a muscular heart to propel it; some of them, however, are warm 
blooded, while others are cold blooded, in other words, the first maintain 
a uniform temperature, 98° F., while the other rises and falls with that of 
the surrounding medium. They are also endowed with the five special 
senses, smell, sight, hearing, taste, and touch, and furnished with two jaws, 
one above or in front of the other, which are frequently supplied with 10 
teeth for the purpose of masticating the food, or to be used as organs of 
offense or defense. In many the teeth are entirely absent, as in birds, etc. 
The Articulata (Lat. ar tic ulus, a joint) are formed of a number 
of pieces or segments united or articulated together. The skeleton, 
when present, is invariably external, and incloses not only the nerv- 
ous system but the muscles which move the body. The various portions 
are articulated together so as to admit of great freedom of motion to 
the body and extremities, the latter of which, when present, are quite 
numerous, never being less than six, and sometimes reaching one hun- 
dred in number, as in the centipede. In the worms and leeches, the body 
is merely surrounded by a soft envelope, in which the segments cannot al- 
ways be readily observed. The blood, which is white, circulates, except 
in the higher forms, without a central organ or heart. The organs of 
vision, taste, hearing, and touch have been observed in them. The jaws, 
usually more than two in number, open laterally. 
The Mollusca (Lat. mollis, soft) are distinguished by negative rather 
than positive characters; they have neither an articulated skeleton nor ver- 
tebral column, and the organs of motion and sensation are of a.low order, 
and some of them are fixed to one spot, except during the earliest 
periods of existence. The body is enveloped in a loose mantle, which in 
some is capable of secreting one or two shells, which afford protection, 
and serve the purpose of an external skeleton. The blood is white or 
bluish white, and propelled by a heart of simple structure. 
The Radiata (Lat. radius, a ray) unquestionably hold the lowest 
rank of the four definite types of structure under which all the higher 
forms of animal organization may be classified. The predominance of 
the vegetative or nutritive apparatus over those of animal life is quite 
conspicuous. The radial symmetry which it presents makes it approxi- 
mate in general resemblance to plants, and on account of this some of 
them have been denominated Zoophytes (Gr. zoon, animal, phyton, 
plant); these are fixed to the ground and have the form of plants. In 
some of the Radiata, as in the sea-urchin and star-fish, the skeleton is 
external, while in the polypi it is sometimes internal. Most of them have 
a mouth and stomach for the reception of food, while others absorb it 
through their exterior, like plants; the radiated character, while readily 
observable in some, is absent in others, and it is this which has given so 
much dissatisfaction and has induced the establishment and recognition 
of a fifth Sub-Kingdom. 
The Protozoa (Gr. protos, first, zoon, animal) are in general exceed- 
ingly minute microscopical objects found specially abundant in water; 
a large proportion of them consist of single cells or aggregation of cells, 
but their animal character is made manifest by their movements and mode 
of nutrition. Prof. Agassiz contends that these minute beings do not 
constitute a natural group; and he believes that they are only imperfectly 11 
understood, and that eventually many of them will be distributed among 
vegetables, and others to one of the four primary divisions of animals. 
CLASSES. 
The Archetype Vertebrata are divisible into four classes, based 
upon the performance of some special action or function peculiar to 
each class. All of these agree in possessing a vertebral column, but differ 
in other peculiarities of structure, as follows: 
The Pisces (Fishes), the lowest class of the Vertebrata, are only formed 
to live in water; they are oviparous (Lat. ovum, an egg, pario, I bring 
forth) ; in other words, all but a few species lay eggs. The vertebrae gen- 
erally present a concave surface to each other, and the space thus formed 
is occupied by a sac of fluid, that gives very great latitude of motion to 
the spine, which is sometimes cartilaginous. The tail is generally expanded 
into a broad fin, and is the principal instrument of progression. In ad- 
dition to this, there are two pectoral and two ventral fins, which aid in 
locomotion. Being strictly aquatic in their habits, they respire through 
the medium of the element in which they live by means of gills. They are 
cold blooded, and the heart is composed of two cavities, an auricle and 
a ventricle, which receive the venous blood from the system, and propel it 
over the respiratory surface whence it is collected into an arterial trunk, 
the aorta, by which it is distributed over the body, without the interven- 
tion of a systemic heart. The body is usually covered with scales. 
The Reptilia (Lat. repto, I creep) include a large class of animals, 
many of which differ so much in form that those who are unacquainted 
with the subject would hardly suppose that serpents, lizards, and tor- 
toises are all arranged under the same head. The vertebrae of the ser- 
pents articulate like a ball-and-socket joint, by which these animals are 
enabled to coil themselves up in the form of a ring. This class is for 
the most part adapted to the surface of the earth, and those which live 
in the water are obliged, with few exceptions, to come to the surface to 
breathe, as they are provided with lungs in place of gills. The general 
habits of all of them are lazy, and in cold and temperate climates they 
pass almost the entire winter in a state of lethargy. With the exception 
of a few species which bring forth their young alive, they are all ovipar- 
ous and cold blooded. The heart usually consists of three cavities: one, 
the systemic auricle, receiving the blood from the body, and another, the 
pulmonic auricle, from the lungs ; both of these cavities communicate 
with a ventricle, whence the blood is propelled through the body as well 
as to the lungs. Certain animals, which were formerly arranged in this 
division have been placed in a separate class; they are 
The Amphibia (Gr. amphi, both, bios, life), so named on account of the 
faculty which these animals possess of living in the water or on the land; 
it includes the frogs, toads, salamanders, etc. During their earlier and 12 
immature existence, as tadpoles, they partake of the character of fishes, 
but eventually undergo a peculiar metamorphosis, during which the ex- 
tremities are developed, and they then approximate to Reptiles in their 
general structure and mode of respiration, and, like them, are oviparous, 
cold blooded, and merely covered with a thin skin. 
The Aves (birds) are formed for rapid motion in the air, and the bones 
of the skeleton are quite light and hollow, which greatly lessen the spe- 
cific gravity of the body. The anterior extremities are invariably con- 
structed so as to aid in flight, while the actions of standing, walking, 
scratching, and swimming demand different modifications of the posterior 
extremities. Their jaws are furnished with a horny bill, varying in form 
according to the nature of the food. The divisions of this class have 
been chiefly founded by ornothologists on modifications of the bill and 
feet. They are oviparous, and the ovum, inclosed in a calcareous shell, 
is perfected by incubation after extrusion from the body. Possessing a 
double circulation, systemic and pulmonic, with a heart having two auri- 
cles and two ventricles, along with the most perfect respiratory appa- 
ratus ; circulation and respiration are rapid, and they are consequently 
warm blooded, their temperature frequently rising as high as 107° F. 
The feathers which cover them, acting as a non-conducting medium, serve 
to retain their heat. 
The Mammalia (Lat. mamma, a breast), so named from possessing 
mammary glands to suckle their young, are the most highly organized 
class of animals. Taken as a whole, they are not characterized so much 
by the possession of any particular faculty as by the perfect combination 
of the different powers, which render the animals belonging to it capable 
of a much greater variety of actions than any others can perform. They 
are distinguished in particular by the high evolution of that portion of 
the brain named the cerebrum, which is regarded as the seat of intelli- 
gence and the reasoning faculties, whereby means are adapted to ends for 
the purposes of the individual. These attributes reach their highest de- 
velopment in man. It is the recognition of these facts which has induced 
the naturalist to place this class at the head of the Animal Kingdom. 
Like Birds, they have warm blood, a heart, with four cavities, two auri- 
cles, and two ventricles, and a perfect pulmonic and systemic circulation. 
Provision is made for the regular renewal of the air in the lungs, not 
only by the movements of the ribs but by the action of the diaphragm. 
The temperature of this class is about 98°. To confine the heat and pre- 
vent its rapid absorption by the surrounding atmosphere in cold climates, 
many of these animals are liberally supplied with hair or fur. The im- 
mense quantities of blubber or fat under the thick skin of the whales serve 
the same purpose. 13 
Sub-Classes. 
The Class Mammalia are divisible into two sub-classes; the first 
of which, the vivipara (Lat. vivus, alive, pario, I bring forth), embracing 
ten orders, bring forth their young alive; the second, the ovovivipara 
(Lat. ovum, egg, vivus, alive, pario, I bring forth), produce living young 
in a more immature state than the former, the egg being developed within 
the body of the parent, without any connection with the womb, by means 
of a placenta; of these there are only two orders.* 
ORDERS. 
The Mammalia are thus divisible into twelve orders, founded upon 
certain well-marked peculiarities of structure., and in arranging them 
advantage is taken of external and easily recognized differences: the 
variations of structure in the extremities, and the arrangement, form, 
and structure of the teeth in particular, serving as valuable guides or 
aids in this respect. It would be interesting and profitable to dwell at 
length on these points and their characteristic manifestations, while re- 
viewing the different orders, but this would consume too much time 
now, and not be in accordance with the plan of the lecture. It will 
suffice to say, in general terms, that the sub class placentalia includes 
animals whose extremities present two specific points of difference, and it is 
therefore divided into, first, the unguiculata (Lat. unguis, the nail or 
claw), including eight orders which have their extremities armed with 
nails or claws, but free for the exercise of touch upon their under surface. 
Six of these orders are Carnivorous, while two of them are Herbivorous. 
2d. The Ungulata (Lat. ungula, a hoof) embrace two orders, having 
hoofed extremities and feeding upon vegetables. The two orders of the 
Implacentalia have extremities which entitle them to be classed with 
the Unguiculata; they vary, so far as their food is concerned, a few 
being Carnivorous, the majority Herbivorous. The teeth of these different 
orders generally correspond with the extremities and with the character 
of the food, being sharp and pointed in those possessing claws and feeding 
on flesh, while they present broad grinding surfaces in the animals having 
hoofed extremities and feeding on vegetables. The Unguiculata are : 
The Bimana (Lat. bis, twice, manus, hand), including the single Genus, 
homo, or man, present as physical characteristic in contradistinction to 
other animals, the maintenance of the erect position; and the possession 
of two hands with an opposable thumb, that enables man to accomplish 
* Prof. Owen arranges the above sub-classes as follows: the first as the Pla- 
centalia (Lat. placenta, a cake), in which a soft vascular body is found adherent 
to the uterus and connected with the foetus by the umbilical cord; the second as 
the Implacentalia, or those without a placenta. The distinction thus established 
is much more satisfactory than the first, from the fact that the young of each sub- 
class are brought forth alive. 14 
a variety of things by its aid which no other creature can effect. He is 
furthermore distinguished for the possession of articulate language or 
speech, and the power of not only communicating his thoughts to his 
fellow-man in his own day and generation, but with the aid of the hand 
in writing, to transmit them to posterity. Not only the character of his 
teeth, but other circumstances prove that he is Omnivorous (Lat. omnis, 
al), voro, I devour), or in other words, he is intended to live on a mixed 
diet, vegetable and animal. 
The Quadrumana (Lat. quatuor, four, manus, hand) embrace mon- 
keys, apes, etc., all of which possess four hands, somewhat, but not ex- 
actly, analogous to the hand of man ; they might be compared indeed with 
as much propriety to his foot as to his hand, as th§y are all used for loco- 
motion. Although able to stand nearly erect, their natural position when 
moving about is mainly on all-fours. 
The Cheiroptera (Gr. cheir, hand, pteron, wing) are animals having 
the anterior extremities, and especially the hands, so modified as to serve 
the office of wings. This order includes the bats, which were formerly 
regarded by naturalists as birds, but the possession of teeth, and suckling 
their young like other Mammalia, clearly demonstrate the class to which 
they belong. 
The Insectivora (Lat. in sect us, an insect, voro, J devour), such ani- 
mals as the hedge-hog, mole, and shrew, feed exclusively upon insects. 
The Carnivora (Lat. carnis, flesh, voro, I devour) have teeth which 
are peculiarly adapted for seizing upon and destroying living prey and 
tearing their flesh. The lion, tiger, bear, dog, seal, etc. all belong to 
this order. 
The Cetacea (Lat. cetus, a whale) were formerly regarded as fishes, 
but the possession of warm blood, bringing forth their young alive, and 
suckling them, prove that they belong to the Mammalia. Those which 
are provided with teeth seize upon large marine animals, while others 
that have none, derive their support from the smaller kinds by engulfing 
them with a large quantity of water in their capacious mouths. There are 
others again that are strictly Herbivorous, which some naturalists arrange 
as a distinct order, the Sirenia. 
The Rodentia (Lat. rodo, I gnaw), comprising rats, mice, beavers, 
squirrels, rabbits, guinea-pigs, etc., are characterized by having two 
large incisors in each jaw separated from the molars by a wide space ; 
these teeth have enamel on their front surfaces only, so that their pos- 
terior border being worn away more than their anterior, they are always 
kept set like a chisel. 
The Edentata (Lat. e, privative or deprived of, dens, a tooth), in- 
cluding the sloth, armadillo, ant-eater, etc., have no incisors or front teeth. 
The two orders arranged as Ungulata are, 
The Paciiydermata (Gr. pachus, thick, derma, skin), distinguished for 15 
the thickness of their skin, and include the horse, hog, tapir, rhinoceros, 
and elephant, the last of which, from the fact of possessing claws, is an 
unguiculated animal. 
The Ruminantia (Lat. rumino, to chew the cud) comprise those 
animals which possess a compound stomach, and who, after their food 
has been taken into the mouth and swallowed, regurgitate it by the 
stomach throwing it back into the mouth to be rechewed as a cud, when 
it is again swallowed, and, by a peculiar elongation of the oesophagus, the 
bolus, in place of entering the first cavity as it did in the previous in- 
stance, passes on to the third. The ox, sheep, deer, etc. are contained 
in this order. The first two of these are named hollow horned, on ac- 
count of their having hollow horns projecting in front of the skull that 
are never shed. The deer, on the contrary, are called solid horned, from 
the fact that the antlers are solid like bone. These are cast or shed and 
renewed each year. All of these animals, with the exception of the camel, 
have no front teeth in the upper jaw. The camel is also unguiculated. 
The Sub-Class Implacentalia embrace the last two orders of the 
MAMMALIA, aS follows : 
The Marsupiata (Lat. marsupium, a pouch) are so named on ac- 
count of the presence of a pouch in the front and lower part of the 
abdomen of the females, which serves as a temporary abode for the young 
after birth. The kangaroo and opossum belong to this order. 
The Monotremata (Gr. monos, one, and trema, perforation) have a 
common outlet for the generative and excVemental products, and in this 
respect they resemble birds. 
The different Orders thus briefly referred to are each divisible into 
FAMILIES. 
Much confusion is induced by the careless manner in which many natu- 
ralists employ the term Family, frequently using it as synonymous with 
Order. Such, however, is not the case; for each Family is made up of 
Genera that resemble each other in certain particulars, and are separated 
from other Genera which belong to the same Order, on account of 
some modification of form or structure. Thus the dog, which belongs 
to the Family Canida; (Lat. canis, a dog), is distinguished from the 
bear, belonging to the Family Ursidte, not only by the form of the 
body, but also by walking upon the ends of the toes in place of the sole 
of the foot; this being due to a structural difference in the shape and 
articulation of the bones in the lower part of the limbs. Both of these 
Families belong to the Order Carnivora. 
GENERA. 
As already stated, the Order Bimana includes only a single Genus, 
Homo, or man. Divisible, however, as most Orders are into Families 16 
embracing several Genera, minor details of structure frequently serve 
as generic characteristics; thus, advantage is sometimes taken of such 
slight anatomical peculiarities as "the number, disposition, or propor- 
tions of the teeth, claws, etc." in the carnivora, to distinguish one genus 
from another. 
SPECIES. 
As the anatomical differences which separate Genera of the same 
Family are so slight, it would be reasonable to infer that the division of 
a Genus in Species must be based upon peculiarities still less marked, 
and such is the case. Thus, "color, size, proportion, etc." serve as means 
for the recognition of different Species of the same Genus. " The principal 
characteristic of species is the power of producing beings like themselves 
who are also productive. A species may be modified by external influ- 
ences, and thus give rise to races or varieties, but it never abandons its 
own proper character to assume another." 
To recapitulate briefly: the Animal Kingdom, embracing all animals, 
recent or extinct, is divisible into Archetypes, according to four general 
plans of construction observable in them; these again into Classes, based 
upon the performance of some special action or function peculiar to 
each class; these into Orders, founded upon certain well-marked 
peculiarities of structure; these into Families, on account of some 
modification of form or structure; these into Genera, to distinguish 
which, advantage is sometimes taken of such slight anatomical pecu- 
liarities as the number, disposition, or proportion of the teeth, claws, 
etc.; and lastly, the latter into Species, in which color, proportion, and 
size serve as characteristic differences. This is the key to the Cuvierian 
Classification of Animated Nature, and which unfortunately many 
persons who have devoted years to the study of natural history apparently 
have the most confused and erroneous ideas in relation to. Comparison 
throughout is the basis upon which the entire system rests, and it has its 
foundation in nature rather than art. 
In conclusion, like a traveler who, on the top of a mountain, taking in 
an extended view of a new and beautiful landscape beneath, observes here 
and there prominent objects of interest, on descending to the plain finds 
an immense number of minor objects claiming his attention, is better pre- 
pared to understand the exact relation one part bears to another, so it is 
trusted that this address may answer a similar purpose to some of you in 
the study of Natural History. In the facts that have been thus imper- 
fectly presented, my aim has been to give them in a plain, simple, and 
comprehensive manner; but embracing, as the remarks have, only a gen- 
eral and hasty survey of leading points, they should be regarded by those 
who may desire to become better acquainted with the subject-matter as 
merely introductory to a regular course of study in this direction.