ITS NEAKEST EXISTING EELATIONS. 83 



pure selection (" artificial " in this instance, but com- 

 ing under the same category of causes of modifica- 

 tion as the " natural selection " of Darwin and Wal- 

 lace), the latter, of inheritance of characters acquired 

 during life, the potency of which has been much 

 called in question of late. 



In Australia, as in America, horses imported by 

 the European settlers have escaped into the unre- 

 claimed lands and multiplied to a prodigious extent, 

 roaming in vast herds over the plains where no 

 hoofed animal ever trod before. 



The nearest approach to truly wild horses exist- 

 ing at present are the so-called Tarpans, which oc- 

 cur in the steppe-country north of the Sea of Azoff, 

 between the river Dnieper and the Caspian. They 

 are described as being of small size, dun color, with 

 short mane and rounded, obtuse nose. There is 

 no evidence to prove whether they are really wild 

 — that is, descendants of animals which have never 

 been domesticated — or feral — that is, descended from 

 animals which have escaped from captivity, like the 

 horses that roam over the plains of America and 

 Australia, and the wild boars that now inhabit the 

 forests of New Zealand. 



Darwin infers that, aboriginally, the horse must 

 have inhabited countries annually covered with snow, 

 for he long retains the instinct of scraping it away 



