INTRODUCTORY. 
23 
The organ of touch is more perfect in animals whose fingers 
are more numerously developed, and which are least covered at 
their tips ;—such as those possessing only a single nail protect¬ 
ing their upper extremities, as in man ; sensation in the toes of 
such as are covered with hoofs, on the contrary, is extremely 
blunted. 
In the dentition given, and the generic characters, the method 
of Cuvier is followed. The arrangement of the figures is in¬ 
tended to represent the upper and under jaw. For example, in 
man, the incisory, or cutting teeth, are in the centre of each 
jaw, and are marked (Plate I. fig. 2—1,) that is, four above 
and four below; the canine, or sharp pointed teeth, are next to 
these, and are marked }-}, (fig. 2 — 2 ,) that is, one on each side 
of the incisory teeth in both jaws; beyond these, and further 
in the mouth, are the grinders, molars, or cheek teeth, marked 
5 Z 5 J (fig- 2 — 3 ,) that is, five on each side of the canine teeth in 
each jaw* making in man a total of thirty-two teeth. The 
Chimpanse, an animal which stands next to man, as approach¬ 
ing nearest to him in his organization, has a similar arrange¬ 
ment in the number and kinds of his teeth. 
The class Mammalia is divided in the following orders by 
Cuvier and Latreille:— 
I. Bimana ; with two hands, of which man is the only spe¬ 
cies. He possesses three kinds of teeth. 
II. Quadrumana ; or animals with four hands, and having 
three kinds of teeth. 
III. Cheiroptera. The general form of these animals is 
adapted for flight; with a fold of skin between their four limbs, 
and two pectoral teats, and they have three kinds of teeth. 
IV. FERiE. The four extremities are formed for walking, 
with three kinds of teeth : the teats vary in number. 
V. Marsupialia. These vary in different genera. The 
young are produced prematurely, and brought to perfection in an 
abdominal pouch which incloses the teats. 
VI. Rodentia. These have two large incisory teeth in each 
jaw, separated from the grinders by a vacant space ; they have 
no canine teeth: the grinders have flat crowns, or, if tubercu- 
lated, they are blunt; the hind limbs are longer than the fore 
ones, and furnished with nailed toes, and varying in different 
species : the teats are also variable. 
