106 NUTRITION. 



tusks or carnivorous teeth, canines ; and the grinders, molars, 

 (Fig. 73.) The incisors (a) occupy the front of the mouth, 

 the upper ones being set in the intermaxillary bones ; they 

 are the most simple and the least varied, have generally 

 a thin cutting summit, and are employed almost exclusively 

 for seizing food, except in the elephant, in which they assume 

 the form of large tusks. The canines (b) are conical, more 

 elongated than the others, more or less curved, and only two 

 in each jaw. They have but a single root, like the incisors, 

 and in the carnivora become very formidable weapons. In 

 the herbivora, they are wanting, or when existing they are 

 usually so enlarged and modified as also to become powerful 

 organs of offence and defence, although useless for mastica- 

 tion ; as in the babyroussa, &c. The molars (c) are the most 

 important for indicating the habits and internal structure of 

 the animal ; they are, at the same time, most varied in 

 shape. Among them we find every transition, from those of 

 a sharp and pointed form, as in the cat tribe, to those with 

 broad and level summits, as in the ruminants and rodents. 

 Still, when most diversified in the same animal, they have 

 one character in common, their roots being never simple, 

 but double or triple, a peculiarity which not only fixes them 

 more firmly, but prevents them from being driven into the 

 jaw in the efforts of mastication. 



219. The harmony of organs already spoken of (22-24) 

 is illustrated, in a most striking manner, by the study of the 

 teeth of the mammals, and especially of their molar teeth. 

 So constantly do they correspond with the structure of the 

 other parts of the body, that a single molar is sufficient not 

 only to indicate the mode of life of the animal to which it 

 belongs, and show whether it feeds on flesh or vegetables, or 

 both, but also to determine the particular group to which it is 

 related. Thus, those beasts of prey which feed on insects, 

 and which on that account have been called Insectivora, such 



