CLASS MAMMALIA 633 



(C) Ungulata, or hoofed animals, such as the pigs, deer, 

 sheep, oxen, horses, and elephants, and 



(D) Cetacea, or whales, which have probably been derived 

 from the unguiculate division. 



1. The Rabbit 



The rabbit belongs to the order of gnawing mammals — the 

 Rodentia or Glires. This order is made up of a number of 

 families, one of which, the Leporid/E, contains about sixty species 

 of rabbits and hares. Rabbits are generally common in North 



Fig. 510. — Lateral view of skeleton with outline of body of the rabbit. 

 (From Parker and Haswell.) 



America, both wild and in a state of domestication. They are, 

 therefore, usually easy to obtain. This fact together with their 

 convenient size have made them favorite objects for the intro- 

 duction of students to mammalian anatomy. The following 

 account, however, is not intended as a laboratory guide, but sim- 

 ply as a means of pointing out some of the more obvious mam- 

 malian characteristics with the aid of an animal that can be 

 examined easily in the class room. 



External Features. — The rabbit (Fig. 510) is a four- 

 footed animal (quadruped) adapted for leaping. It possesses 

 an external covering of hair, two large external ears, or pinna, 



