ORIGIN OF THE HORSE. 11 



asses are descended. The Mountain Zebra oc- 

 cupies the same position for that species. Spe- 

 cific differences between the horse and the ass 

 are many, but the chief perhaps are that the 

 ass has but ^ve lumbar vertebrae, the horse 

 six ; the ass has chestnuts on two legs, the horse 

 on all four; the ass brays, the horse neighs. 

 Position is accorded Prjevalsky's horse as de- 

 fined in part because it has only five lumbar 

 vertebrae, yet its other characteristics place it 

 among the true horses. 



Crossing is freely accomplished among mem- 

 bers of the three species of this genus. The re- 

 sult of such crossing is termed a hybrid. The 

 most common is between the horse and the ass 

 and this mating appears to have been made at 

 a very early date, though in which direction we 

 do not know. Progeny of the male ass and 

 mare is called a mule, that of a stallion and a 

 female ass a hinny. Progeny begotten by the 

 male zebra from mares is now comparatively 

 common and is termed zebroid. In all cases 

 these hybrids are absolutely sterile. Allega- 

 tions to the contrary have been made, but proof 

 without flaw or loophole is so far wanting. 



War and the chase having been, beyond that 

 of food for man, the primal uses to which the 

 horse was put, and as improvement would 

 naturally follow domestication, we must look 

 in Asia or North Africa for the first advances 

 toward the strength to carry men and later in 



