Rhinoceros, Swine. 93 



enormous thickness and often folded. The leading 

 characteristic is the long epidermal horn which is 

 rooted in the dermis on the upper surface of the nose. 

 This in structure consists of a tuft of confluent hairs, 

 and sometimes grows to several feet in length, and is 

 of great hardness; the horn is always medial, and 

 usually single, when two exist they are placed one in 

 front of the other. At one time a species of rhino- 

 ceros clothed with a woolly coating inhabited Great 

 Britain and the northern parts of Europe and Asia, 

 but it became extinct in prehistoric times. 



All these odd-toed ungulates have at least twenty- 

 two vertebrae in their trunk, interposed between the 

 neck and the sacrum, and they all have a bony knob 

 or third trochanter on the outside of the shaft of the 

 thigh bone for the attachment of muscles. See fig. 

 44, also fig. 41. 



The second sub-order of hoofed animals includes 

 those whose toes are. in even numbers, two or four, 

 and are laterally symmetrical (when there are four, 

 two are in front and two behind). They have for the 

 most part nineteen dorso-lumbar vertebrae, and none 

 of them have the protuberance on the thigh-bone 

 referred to above. Many of them have horns, but 

 these are always on the forehead, and one on each 

 side, never median as in the rhinoceros. 



59. Swine and Hippopotami. There are two very 

 well-marked divisions of these even-toed ungulates. 

 In one of these the animals have simple stomachs, 

 and the grinding teeth have little knobs or protuber- 

 ances on their surfaces, hence these are called Buno- 

 donts j in the other group the stomachs are complex, 



