312 BIOLOGY FOR BEGINNERS 



rodents for their well-known occupation of gnawing their way 

 through life. 



The Ungulates (hoofed animals) include some of our commonest 

 domestic animals, such as the horse, pig, cow, sheep, and goat. 

 Among its familiar wild members are the deer, antelope, tapir, 

 rhinoceros, hippopotamus, giraffe, camel, zebra, etc. All of 

 these most of us have seen in circuses and zoological gardens. 

 These animals live on vegetable foods and have back teeth (molars) 

 fitted for grinding. Most of them have a side-wise jaw motion 

 which also aids in this process. Their feet are encased in hoofs, 

 and the limbs are never used for prehension, being adapted only 

 for swift locomotion. There are never more than four toes in use 

 and frequently fewer are developed. 



The Ungulates are divided into two groups: 



1. Odd toed in which the weight is borne on one toe though 

 others may be present. They include the horse, rhinoceros, and 

 tapir. 



2. Even toed in which the third and fourth toes bear the weight, 

 though two others are usually present. 



These even-toed ungulates are again divided into two groups 

 called 



1. The non-ruminants (pig, hippopotamus). 



2. The ruminants (cow, sheep, deer, etc.). 



The ruminants are so called from their habit of chewing their 

 food as a " cud." A cow, for example, first compresses its food 

 into a ball, swallows it into the first of the divisions of its four- 

 chambered stomach where it is stored. Later it is forced back into 

 the mouth, chewed thoroughly and swallowed again, but into 

 another stomach chamber, where the final processes of digestion 

 are completed. The advantage of 'this peculiar arrangement is 

 that much food can be hastily eaten and stored, to be chewed later. 

 This, for an animal which feeds in flocks, on bulky vegetable food 

 is of great importance, since it can get its share in haste and chew 

 it at leisure. The ungulates include most of our domestic animals. 

 From them we obtain the bulk of our animal food and clothing, 

 leather, horn, and other products and among them we find nearly 



