140 COMPARATIVE DENTAL ANATOMY 



The common mice have the same formula. In 

 some the incisors are grooved and the molars may 

 be without roots. The field mice have a trefoil 

 pattern of the molars, or are "triangular. There 

 are many other living members of this order, but 

 all have similar dentitions to these well-known ex- 

 amples. The fossil progenitors of this order 

 were often of gigantic size. Some were highly 

 specialized, and others with composite features 

 resembling those of their living descendants. 



The Carnivora is the great order of the flesh- 

 eaters, the destroyers of animal life. It com- 

 prises the true Cats, the Felidce, the Lion, Tiger, 

 Leopard, the common cat, etc. ; the CanidcE, dogs, 

 wolves, foxes, etc. ; the Ursidce, bears, raccoons, 

 etc. They subsist upon flesh, and to obtain this 

 must destroy animal life, and are well equipped 

 for the purpose by a highly specialized dentition, 

 by their sharp, strong claws, and by their 

 strength, speed, and agility. They are simply 

 organized and highly specialized. There is little 

 or no mastication of food and little digestion re- 

 quired, so the intestines are short, and the whole 

 organization indicates a simple diet which is 

 easily appropriated. In dental organization, the 

 Carnivora stand at one extreme end of high spe- 

 cialization, as the Herbivora do at the other, — the 

 flesh-eaters as opposite to the plant-eaters. We 

 notice first the special hinge-like structure of the 



