30 MAMMALIA. 
may be deduced the nature of its food, and the cctsequent structure cf its 
digestive apparatus. On these characters are founded the division of mam- 
miferous animals, into orders. 
The degree of perfection of the organs of touch, may be estimated accord- 
ing to the number and mobility of the fingers, and according to the greater 
or less depth with which their extremities are covered by the nail or hoof. 
A hoof, for instance, which envelopes that part of the extremity which 
would otherwise touch the ground, blunts the feeling, and renders the foot 
incapable of seizing. The opposite extreme is, when only a single lamina 
covers the upper surface of the end of the finger or toe, leaving to the other 
all its sensibility. The nature of the food may be judged of by the appears 
ance of the molar teeth, to the form of which the articulation of the 
jaws always corresponds. For cutting flesh, the teeth require to be edged 
like a saw, and the jaws to close vertically, like scissors. To bruise grains 
or roots, it is requisite that the molars have a flat crown; that the jaws ° 
should move horizontally, as well as vertically ; and that the teeth should 
be composed of parts of unequal hardness, to give them the necessary 
inequalities for this operation. The hoofed animals are all necessarily 
herbivorous, and possess teeth of this description, since the structure of their 
feet precludes them from seizing living prey. 
Animals with unguiculated toes or fingers, on the contrary, are suscepti- 
ble of more variety in their modes of subsistence; for, besides the form 
of the molar teeth, they differ materially among themselves in the mobility 
and delicacy of their toes or fingers. There is one characteristic, however, 
which exercises a mighty influence on the dexterity of the animals possess- 
ed of it, and which multiplies or greatly varies their Anodes of action. This 
is the faculty of opposing a thumb to the other fingers, and of thus being 
enabled to seize with facility the most minute objects. This opposition 
of a fifth member to the other four, constitutes what is properly called the 
hand, an organ which is carried to the highest degree of perfection in man, 
in whom alone the anterior extremities are free. 
These various combinations strictly determine the nature of the different 
mammiferous animals, and afford the characteristics from which orders 
are formed. In the following pages, the Mammalia will be arranged under 
the following orders: 
Orver I. BIMANA, Orver VI. GLIRES, 
“ IT, QUADRUMANA, « VII. EDENTATA, 
“ JIT. CHETROPTERA, « VIII. PACHYDERMA. 
“« IV. FERA, « 1X. RUMINANTIA 
“~  V. MARSUPIALIA, « XI CETACEA. 
The total number of mammiferous animals described, according to Des- 
marest, is about eight hundred and fifty, including, however, many species 
imperfectly ascertained, and the fossil Mammalia; of which, belonging t¢ 
the onder Quadrumana, are one hundred forty-one,—Cheiroptera, ninety 
