438 THE MULTIPLE ORIGIN OF HORSES AND PONIES. 



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

 mate and the land connections between the Old World and the New 

 were very different from what they are to-day. One result of these 

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

 to the great Ice age — it was possible for American horses to find their 

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

 immigrants {Equus fitenonis) has left its remains in the Pliocene 

 deposits of Britain, France, Switzerland, Italy, and the north of 

 Africa. A^^iile E. stenonis was extending its range into Europe and 

 Africa, two others (E. sivalensis and E. namadieus) were finding 

 their way into India, and yet other species were doubtless 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 knoAV that before the beginning of the historic age horses had 

 become extinct in North America, but w^e 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. sivalensifj and 

 E. namadieus, became extinct, and that E. slfrwnis g-ave rise through 

 one variety {E. rohi/stus) to the modern domestic breeds, and by 

 another {E. liqeris) to the Burchell group of zebras. E. sivalensis, 

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

 and certain prehistoric South American species, w^as 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 

 preorbital depression, and in some of the horses of southeastern Asia 

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

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

 are large functional first premolars. It is hence possible that lineal 

 but somewliat modified descendants of E. siralens!s of the Indian 

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

 ant of IIii)pari()u. 



We are, however, more concerned with the aucestors of the domestic 

 horses of Euroi)e and North Africa than with oriental horses. 



Froui osseous remains already found we know horses were widely 

 distributed over Eurojx^ duriug the Pleistocene period, and that they 

 were es])ecially abuudaiit iu the south of Frauce in post-Glacial times. 

 It has not yet, however-, been determined how numy species of horses 

 inhabited Kurope during and iunnediately after the Ice age, nor yet 

 to which of the |)i'e-( ilacial species prehistoric horses were genetically 

 related. Bones and teeth from deposits and caves in the south of 



