Chap, iv.] TEETH OF MAMMALS. 151 



domestic pig, from eight to ten inches long ; they are 

 often exceedingly sharp,, and are capable of inflicting 

 on those whom they attack severe and deep wounds. 

 In the males of the anthropoid apes the canines are 

 always much larger than in the females, and as they 

 are not developed till later, we are justified in 

 believing that they are sexual weapons of attack, by 

 which the males are aided in fighting with one 

 another for the possession of the females. 



The molars again present us with indications of 

 differences in the form of the teeth corresponding to 

 differences in the character of the food ; at the same 

 time, the very greatest care must be taken in esti- 

 mating the kind of food from the form of the teeth, 

 and at all times, where it is possible, the general 

 arrangements of the alimentary canal must be steadily 

 borne in mind. Four chief types may, however, be 

 easily distinguished (1) carnivorous, (2) insecti- 

 vorous, (3) frugivorous, (4) herbivorous. The 

 molar or premolar tooth of the dog, which has, since 

 the time of Cuvier, been distin- 

 guished as the carnassial, is 

 modified to form a sharp blade, 

 and is continued behind into a thick 

 tubercle (Fig. 67; A). 



The typical insectivorous tooth 

 is distinguished by the development 

 of four or five sharp cusps (Fig. 66) ; F3 gj Tootl1 

 in the frugivorous forms the cusps 

 are not so distinct, nor so sharp, and are more con- 

 nected with one another by more or less distinct 

 ridges. 



The most essential point in the arrangement of 

 the herbivorous or grinding molar tooth is the dis- 

 position of the several constituent tissues of which it 

 is made up ; the large squarish solid structure, formed 

 of pillars and ridges, is composed of enamel and 



