CHAPTER X 



ODD-TOED UNOULATES (PERISSODACTYLA) 



The living members of this group of Ungulates 

 are the tapirs, rhinoceroses; and horses. Sir Richard 

 Owen gave them the name of '' Perissodactyla ^^ or 

 " uneven-fingered/^ because of the structure of 

 their limbs, which are symmetrical to an axis passing 

 through the middle finger or third digit, and this 

 digit is larger and more prominent than any of the 

 others. In all existing Ungulates the thumb or first 

 digit is completely suppressed, and the limb is en- 

 tirely supported on the nails of the fingers and toes, 

 which have become enlarged to form hoofs. In the 

 Kquidse, or horses, zebras, and asses, the third digit 

 is the only functional toe, the second and fourth 

 digits being reduced to splint bones. 



Tapirs. 



Neither the tapirs nor rhinoceroses can be said to 

 be common animals, but they are specially interest- 

 ing to us as very ancient connections of the horse 

 family, because they are among the oldest existing 

 forms of mammalia, and because of the peculiar 

 structure of the nose and upper lip, which forms a 

 short trunk, similar to that of the elephant. 



