MAMMALS 



269 



All flesh-eating 

 mammals are wan- 

 dering hunters ; 

 many, as the bear 

 and lion, have 

 homes or dens to 

 which they retreat . 

 Some, as bears and 

 raccoons, live part 

 of the time upon 

 berries and fruit. 



Rodents. Mam- 

 mals known as 

 rodents have the 

 teeth so modified 

 that on both up- 

 per and lower jaws 

 two prominent 

 teeth, incisors, are 

 used for gnawing. 

 These teeth keep 

 their chisel-like 

 edges because the back part of the teeth is softer and wears 

 away more rapidly than the front part. The canine or dog teeth 

 are lacking. We are all familiar with the destructive gnawing 

 qualities of one of the commonest of all rodents, the rat. 



Ungulates: hoofed mammals. This group includes most of 

 the domesticated animals, as the horse, cow, sheep, and pig. 

 Many of these animals came under the subjugating influence of 

 man and now they form an important part of the world's wealth. 



The order of ungulates is a very large one. It is characterized 

 by the fact that the nails have grown down and become thickened 

 as hoofs. In some cases only two (the third and fourth) toes are 

 largely developed. Such animals have a cleft hoof, as the ox, 

 deer, sheep, and pigs. They are the even-toed ungulates. The 

 deer family contains the largest number of species and individuals 

 among our native forms, and in fact the world over. Among them 







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of Biological Survey 



The beaver is a rodent. 

 How does he differ from 

 other mammals ? What 

 kinds of food does he eat? 



U. S. Bureau of Biological Survey 



