CHAPTER II. 



THE EXISTING EQUIDAE. 

 Hark ! I hear horses. Macbeth, iii. 8. 



The early ancestors of the horse which first crossed from the 

 western hemisphere into Asia have had a much more successful 

 career than their American cousins, for in spite of various gi'eat 

 flesh-eatiog animals which once preyed upon their ancestors 

 in Asia and Europe, and still continue to do so down to our 

 own day in Africa, the genus Equus at this present moment 

 (without including the probably extinct quagga) comprises at 

 least some fifteen species or subspecies: — (1) Equus cahallus 

 (the horse) ; (2) E. cahallus celticus (the Celtic pony discovered 

 recently by Prof Ewart); (3) E. przeiualskii (Prejvalsky's horse); 

 (4) E. kiang (the kiang); (5) E. onager (Indo-Persian wild ass) ; 

 (6) E. hemippus (Syrian wild ass); (7) E. asinus (the African 

 wild ass) ; (8) E. somalicus (the Somali wild ass) ; (9) E. grevyi 

 (Grevy's Imperial or Somali zebra); (10) E. zebra (Mountain 

 zebra); (11) ^. crawshayi; (12) E.foai; (13) ^. granti (Grant's 

 zebra); (14) E. chapmani (Chapman's zebra); (15) E. hurchelli 

 (Burchell's zebra); (16) E. quagga (the quagga). 



HORSES. 



We have seen that in the true Equidae each foot consists 

 of a single complex digit, but with vestiges of the second 

 and fourth digits, and there is a callosity on the inner side 

 of the fore-leg above the carpus. Besides this there is in 

 the common horse {E. cahallus) also a callosity on the back and 

 lower surface of each fetlock joint in the centre of the tuft of 

 hair which covers that part, and a callosity on each hind-leg a 



