60 THE PEJEVALSKY HOESE. 



a suspicion need not be entertained, since hybrids between two 

 species seldom occur without human interference. 



At the present time, Flower's objections fall to the ground, inas- 

 much as we now possess over ten skins and about ten skulls of E. 

 prjeralskii, from which it is easy to demonstrate the constancy 

 of the characteristics of the species. 



The external characters, as already given, lead to the conclusion 

 that the most important among them and those which are to he 

 considered as constant are : The considerable size of the head ; the 

 absence of a fore-lock ; the upright mane ; the dorsal and shoulder 

 stripes ; the characteristic form of the tail, which carries some of 

 the features of the tail of the onager ; the size of the ear (smaller 

 than that of the ass and the onager) ; the colour of the trunk ; 

 the colouration of the lower part of the limbs ; and the striping 

 of the limbs. Other, and less important, features, such as certain 

 differences of colouration, are to be regarded as individual varia- 

 tions. Craniological and craniometric investigations, as well as 

 the examination of the skeleton, lead to the conviction that E. 

 ■prjevahkii represents a special and peculiar form of horse which 

 constitutes a separate species or race — the exact term matters not : 

 (Matscbie designated all the forms commonly received as species 

 of the genus Equus as " local races "* of Equus standing in 

 close affinity to E. cahaUus). 



The constancy of the structural features and their chai'acters, 

 but mainly the area of geographical distribution of E . prjevalftkii, 

 indicates that it is really a wild species of horse, and not a hybrid 

 between the kiang and the domestic horse, as some zoologists have 

 supposed. If the hypothesis that it is a hybrid were correct, how 

 comes it that the Prjevalsky horse is not met with everywhere 

 where the kiang dwells ? As is well known, the kiang has a much 

 wider distribution than has the wild horse. Moreover, the Prjeval- 

 sky horse lives in herds in which mares with foals are found. This 

 is not conqDatible with the infertility of the hybrid of the ass and 

 the horse. 



From the above, it follows tliat E. prjevalskii is a separate 

 form — species or race — of the genus Equus ; equivalent to the 

 other species or races, such as the kiang, the onager, the ass, &c. 

 The species is of extraordinary interest, since, in it, the characters 

 of the domestic horse (presence of callosities on all four limbs) are 

 mixed with features reminding one of the Asiatic ass (mane, form 

 of tail). These characters, and especially the form of the tail, do 

 not agree perfectly with the like features in the ass, but form 

 something intermediate between the characters of the horse and 



* Op. cit. p. 208. 



