THE FORERUNNERS OF THE HORSE 249 



After remarking that the modern horse dates 

 back to the Pleistocene, or Quaternary, epoch, but 

 is unknown in the Pliocene, Prof. Boule observes 

 that "it is found at Chelles and in most of the 

 deposits of the great interglacial period. It persists 

 right through the Quaternary, everywhere in 

 abundance. It is represented in the Middle Pleisto- 

 cene by races or varieties, to which it is possible 

 to affiliate certain modern races or varieties. 

 Finally, it seems that the evolution of this useful 

 and interesting animal continues to the present day, 

 and that under human influence it will still continue 

 to progress." 



That the extinct Indian E. sivalensis and E. 

 namadicus, which, as already mentioned, differ 

 from one another in the length of the grinding 

 surface of the anterior pillar of the upper cheek- 

 teeth (this being short in the former and long in 

 the latter), gave rise to successors seems almost 

 certain. At one time I suggested 1 that the kiang 

 might be derived from E. sivalensis ; but the cheek- 

 teeth of the former are so much smaller than those 

 of the latter, that this seems unlikely. A latter 

 suggestion is that if the Arab be specificially dis- 

 tinct from E. caballus it may have originated from 

 the Siwalik species, probably through the later 

 Narbada horse. 



1 Palaontologia Indica (Mem. GeoL Surv. India), ser. 10, vol. ii. 

 p. 89, 1882. 



