IN THE LOWER ANIMALS, ETC. 220 



but as I wish to stow their relations to the human 

 dentition, I shall restrict my remarks mainly to 

 the teeth of those animals which respectively ex- 

 hibit, in greatest perfection, the three distinct 

 types of teeth in the human species : viz., incisors, 

 canines, and molars. 



As the teeth determine the nature of the food, 

 there is a necessary connection between their 

 structure and the development of the organs of 

 touch, on which the degree of abihty and address 

 of the animal so much depends. 



The amount of perfection in these organs is to 

 be measured by the number and flexibility of the 

 digits, and the extent to which the nail or hoof 

 encases the extremities. In the ungulated animals 

 the hoof (entire or divided, as seen in the horse 

 and ox respectively), envelopes the foot, limiting 

 its sensibility, and rendering it incapable of seizing 

 a living prey. Hoofed animals are, therefore, of 

 necessity herbivorous, and they are provided with 

 flat-crowned grinding teeth, adapted to the bruising 

 of roots, seeds, or grass. Animals with unguicu- 

 lated digits exhibit much greater variety in their 

 habits, and in the nature of their food, and they 

 differ greatly in the amount of flexibiUty and 

 sensibility bestowed on their extremities. 



The carnivorous tribes are furnished with claws 

 adapted for securing their prey, an organization 

 which has its highest development in the cat 

 family, — whose hooked talons being retractile, are 



