444 THE MULTIPLE ORIGIN OP HORSES AND PONIES. 



verted to the wild state." Against this view I may mention (1) that 

 all the wild horses are of a yellow-dnn color, and that, though those 

 to the west of Kobdo difl'er in tint from those to the east, the eastern 

 and Avestern varieties seem to be connected by the less specialized 

 variety to the south of Kobdo; (2) that travelers in Central Asia 

 all agree in stating that the Mongolian ponies vary greatly in color — 

 in a Cliinese hynm known as the " Emperor's Horses " as many as 

 thirteen colors are referred to; (3) the descendants of the horses 

 which escaped from the Spaniards in America after several centu- 

 ries of freedom were of all sorts of colors; and (4) in horses which 

 live in subarctic areas the hair at the root of the tail tends to increase 

 so as to form a sort of tail lock, which when caked Avith snow pro- 

 tects the hind (juurters during snoAvstorms; the complete absence of 

 this tail lock — fairly Avell developed in one of my Mongolian 

 ponies — is a very strong argument against the assumption that 

 Prjevalsky's horse is nothing more than a domesticated breed that 

 has rcA'erted to the Avild state. 



The Avild horse of the (xobi Desert is certainly the least specialized 

 of all the horses living at the present day. In being of a yelloAv-dun 

 color, in shedding annually the hair of the mane and the hair from 

 tlie upper two-thirds of the tail, in having ergots and chestnuts on 

 the hind as Avell as on the fore limbs, and in haA^ng canines and 

 fairly large upper first premolars, Prjevalsky's horse is distinctly 

 primeval. Only in the all but complete absence of stripes and in 

 having very long poAverful jaAvs armed with relatiA^el}^ large teeth 

 can the Gobi horse be said to be specialized. 



It is extremely probable that Prjevalsky's horse Avas familiar to the 

 troglodytes Avho inhabited the Rhone Valley in prehistoric times. 

 One might eA^en go further and say that in fig. 1, from an engraving 

 in the caA'e of I^a JNIouthe, Ave haAe a fairly accurate representation 

 of the head of Prjevalsky's horse. 



It is, of course, impossible to say which of the recent breeds are 

 most intimately related to the Gobi horse. Though the head and 

 ears are suggestiAe of some of the heavier occidental breeds, in its 

 trunk and limbs it more closely resembles Mongolian and Korean 

 horses, some of which, like Prjevalsky's horse, decidedly differ from 

 Shires and Clydesdales in having a small girth oAving to a Avant of 

 depth of body. To which domestic breeds the Avild horse has con- 

 tributed characters Avhich will probably become more manifest after 

 he has lived for some time under domestication. That heavy occi- 

 dental breeds are not pure descendants of Prjevalsky's horse is sug- 



« It was formerly stated that the wild horse was simply a hybrid between a 

 Mongolian pony and a kiang. I recently showed that a hybrid of this kind is 

 quite different from the wild horse. See Proe. Roy. Soc. Edln., Vol. XXIV. 

 part V, 190L'-3, and Nature, Vol. LXVIII, p. 271. 



