42 



THE HORSE 



CHAPTER II 



THE HORSE AND ITS NEAREST EXISTING RELATIONS 



The tapirs (Family Tajnridre) — Characters, species, geographical and 

 geological distribution — The rhinoceroses (Family RMnocero- 

 tided) — The horses (Family Equida?) — Their immediate predeces- 

 sors—The hipparions or three-toed horses of Europe and America 

 — Existing species of horses— The horse (Equus caballus) — Wild, 

 domesticated, and feral horses — Wild asses — Equus liemionus of 

 Asia and its varieties — The African wild ass and the domestic 

 ass (Eqmts asi nus) - Striped members of the equine family — 

 Zebras and quaggas {Equus zebra, E. burchelli, E. grevyi, and 

 E. quag g a) — Hybrids or mules — Aptitude for domestication only 

 found in certain members of the family. 



As shown in the last chapter, the Perissodactyle 

 ungulates, by various and gradually progressing devia- 

 tions from the common original type, began at a very 

 early age to break up into several groups, some of which, 

 after undergoing a considerable degree of specialisation, 

 have become extinct, without leaving successors ; but 

 three of these modified types, already distinct at the 

 close of the Eocene period, have continued up to the 

 present day, gradually, as time advanced, becoming more 

 and more divergent from each other. These are now 



