160 VEGETARIANS AND THEIR TEETH 



warm-blooded hairy quadrupeds which suckle their young 

 and are called " mammals " (for which word perhaps 

 " beasts " is the nearest Anglo-Saxon equivalent) show in 

 different groups and orders a great variety in their teeth. 

 The birds of to-day have no teeth, the reptiles, amphibians, 

 and fishes have usually simple conical or peg-like teeth, 

 which are used simply for holding and tearing. In some 

 cases the pointed pin-like teeth are broadened out so as to 



FIG. 26. Side view of the skull of a clouded tiger (Felis nebulosa] 

 to show the teeth, inc. 3. The three incisors. can. s. Upper 

 canine, corner-tooth, or dog-tooth, can. i. Lower canine, m. s. 

 The four upper molars or cheek-teeth (called "grinders " in herbi- 

 vorous animals), m. i. The three lower molars or cheek teeth. 



be button-like, and act as crushing organs for breaking up 

 shell-fish. The mammals alone have a great variety and 

 elaboration of the teeth. 



In shape and size, as well as in number, the teeth of 

 mammals are very clearly related to the nature of their 

 food in the first place, and secondly to their use as weapons 



