438 THE MULTIPLE ORIGIN OF HORSES AND PONIES. 



When true horses first made their appearance in America the cli- 

 mate and the hmd connections between the Okl Workl and the New 

 Avere very different from what they are to-da3\ One resnlt of these 

 differences was that before the close of the Pliocene period — i. e., prior 

 to the great Ice age — it Avas possil)le for American horses to find their 

 way into Asia and thence into Enrope and Africa. One of the earlier 

 immigrants (Equvs stenonh) has left its remains in the Pliocene 

 de])()sits of Britain, France, Switzerland. Italy, and the north of 

 Africa. While E. xtenonh was extending its range into Enrope and 

 Africa, two others {E. sivalenfiis and E. iiamadiens) were finding 

 their way into India, and yet other species were donbtless settling in 

 eastern Europe and central Asia. 



It may hence be safely assumed that as Africa now contains several 

 specie of zebras, Europe at the l>eginning of the Pleistocene period 

 was inhabited by several species of horses. 



We know that before the beginning of the historic age horses had 

 become extinct in North America, but we have not yet ascertained 

 what was the fate of the equine species which reached, or were evolved 

 in, the Old World before or during the great Ice age. It is believed 

 by some paleontologists that the Indian species, E. sivalensit; and 

 E. namafh'cns, became extinct, and that E. sienonh gave rise through 

 one variety {E. rohustus) to the modern domestic breeds, and by 

 another {E. Jigeris) to the Burchell group of zebras. E. sJ/u/Jc/isJ.'^, 

 unlike E. stenonis^ but like the still earlier three-toed horse Hipparion 

 and certain prehistoric South American species, was characterized 

 by a depression in front of the orbit for a facial gland (probably 

 similar to the scent gland of the stag), and usually by large first 

 premolar (wolf) teeth in the upper jaw. In some recent horses 

 having eastern blood in their veins there seems to be a vestige of the 

 l)re()rl)ital depression, and in some of the horses of southeastern Asia 

 (e. g., Java and Sulu ponies), as in some zebras (e. g., Grevy's zebra 

 and a zebra of the Burchell type found near Lake Baringo), there 

 are large functional first ])remolars. It is hence possible that lineal 

 but somewhat modified descendants of E. Kiralenxi.s of the Indian 

 Pliocene may still survive, and that E. sivalensiH was a lineal descend- 

 ant of Hipparion. 



AVe are, however, more concerned with tlie ancestors of the domestic 

 horses of Europe and North Africa than Avith oriental horses. 



From osseous remains already found we know horses Avere widely 

 distributed over Europe during the Pleistocene period, and that thej^ 

 were especially abundant in the south of France in post-Glacial times. 

 It has not yet, hoAvever, been determined hoAv many species of horses 

 inhabited Europe during and immediately after the Ice age, nor yet 

 to Avhich of the pre-Glacial species prehistoric horses were genetically 

 related. Bones and teeth from deposits and ca\'es in the south of 



