Il] THE EXISTING EQUIDAE 43 



Gmelin and Pallas), with its forelock and its horse-like tail, 

 were not genuine wild tarpans, but belonged to the mixed herds 

 of eastern Russia. We must therefore reject Salensky's view 

 that the Moscow tarpan represents a variety of Equus distinct 

 from Prejvalsky's horse, by being more specialized towards 

 the side of the horse. The hypothesis that it was a cross 

 between the true tarpan and a feral horse will likewise account 

 for Czerski's conclusions that it approaches the Arab on the 

 one side and the British ponies on the other, for, as has been 

 already pointed out, Arab horses sometimes lack the hock 

 callosities. We shall presently find that mouse-colour the 

 hue of the Moscow tarpan when found in horses is an 

 indication that crossing has taken place. Later on in this 

 investigation it will be shown that mouse-colour and dark 

 mouse-colour in horses are a sure indication of an intermixture 

 of breeds. 



We may therefore conclude that whilst the tarpan of 

 eastern Asia and the Prejvalsky horse with black legs from 

 Zagan-norr Lake are identical, we must hold that the tarpans 

 of eastern Europe and western Asia have probably been largely 

 crossed with escaped domestic animals for at least two 

 centuries, and probably much longer. 



To the three kinds of horses which have been just set forth 

 above I shall venture to add a fourth Equus caballus libycus. 



ASSES. 



Side by side with Prejvalsky horses the brothers Grijimailo 

 found two varieties of wild asses in the desert of Dzungaria. 

 The wild asses of Asia fall into a group distinct from those 

 of Africa; the older zoologists divided them into E. kiang, 

 E. onager, and E. hemippus, which were regarded by some as 

 distinct species, but by others as merely races of the same 

 species, the Equus hemionus of Pallas. The best modern 

 authorities now make at least five subdivisions 1 , E. hemionus, 

 E. hemionus kiang Moorcroft, E. onager, E. onager indicus, and 

 E. onager hemippus, whilst of course there may be other races 

 as yet unidentified. All have a dorsal band, but no shoulder 



1 Dr W. T. Blanford, F.R.S. (Indian Mammalia, p. 470, 1891) holds that 

 all are simply local races of the same species (E. hemionus}. 



