PERISSODACTYLA. 



323 



furnished with three toes each, encased in hoofs. The nasal 

 bones usually support one or two horns, composed of longi- 

 tudinal fibres, which are agglutinated together, and are of the 

 nature of epidermic grow^ths, somewhat analogous to hairs. 

 The Ehinoceroses live in marshy places, and subsist chiefly 



Fig. 626.— A, ,Umler,s-ufrface of the skull of RliUwccros Etrmcus, one-seventh of the natural 

 size— Pliocene, Italy ; b, Crowns of the three true molars of the upper .I'aw, left side, of 

 FMiwceros -niegcu-hiims (R. leptorhinus, Falconer), one-half the natural size— Pliocene, France. 

 (After Falconer.) 



on the foliage of trees. They are exclusively confined at the 

 present day to the warmer parts of the Old World ; but an 

 extinct species {Rhinoceros tichorhinus) formerly inhabited 

 England, and ranged over the greater part of Europe. 



The genus Rhinoceros appears for the first time in the 

 Miocene Tertiary, and still survives ; while it is represented 

 in the earlier period of the Eocene by allied genera. Through- 

 out its long range the genus exhibits a considerable amount 

 of variability, and even the now existing species differ from 



