2/2 COMPARATIVE ZOOLOGY 



But they rarely form an unbroken series. 82 The teeth 

 implanted in the premaxillary bone, and in the corre- 

 sponding part of the lower jaw, whatever their number, 

 are incisors. The first tooth bjehind the premaxillary, if 

 sharp and projecting, is a canine. 



nts 



FIG. 233. Teeth of the right lower jaw of adult male Chimpanzee (Anthropopithecus 

 troglodytes), natural size. The molar series does not form a curve, as in Man. 



Each tooth has its particular bony socket. 83 The 

 molars may be still further strengthened by having two 

 or more diverging fangs, or roots, a feature peculiar to 

 this class. The incisors and canines have but one fang ; 

 and those that are perpetually growing, as the incisors 

 of rodents and elephants, have none at all. The teeth 

 of flesh-eating mammals usually consist of hard dentine, 

 surrounded on the root with cement and capped with 

 enamel. In the herbivorous tribes, they are very com- 

 plex, the enamel and cement being inflected into the 

 dentine, forming folds, as in the molar of the ox, or 

 plates, as in the compound tooth of the elephant. This 

 arrangement of these tissues, which differ in hardness, 

 secures a surface with prominent ridges, well adapted 

 for grinding. The cutting teeth of the rodents consist 

 of dentine, with a plate of enamel on the anterior sur- 

 face, and the unequal wear preserves a chisel-like edge. 



