MULES AND OTHER HYBRIDS 233 



zebra, namely, the dewlap and the reversal of the 

 spinal hair, have been eliminated in the hybrid ; and 

 it is noticeable that the hair along the spine, especi- 

 ally on the croup, is as long as in the foal of Grevy's 

 zebra. The two foals are not exactly alike, differ- 

 ences in detail being detectable everywhere. The 

 ears, for example, are smaller, their basal stripe is 

 narrower and blacker, the shoulder-stripe is shorter, 

 the spinal crest less pronounced, and the legs are 

 less strongly banded in the quagga than in the 

 zebra foal. The resemblance, nevertheless, between 

 the two is strikinor." 



Although the aforesaid hybrid between the 

 Somali wild ass and the zebra is the only known 

 example of such a cross, mules between the domes- 

 ticated ass and zebra have been known from the 

 time of Cuvier. A hybrid of this nature, whose 

 male parent was a black Spanish ass, described by 

 Cuvier himself, is stated by Mr. Pocock to have 

 been like the product of the Somali wild ass and 

 zebra, except that, when adult, the ground-colour 

 was dark grey, even on the legs, and there were 

 spots at the base of the tail. Both these hybrids 

 lacked the white ear-tip of the zebra and the white 

 muzzle of the ass. 



All these hybrids agree in the absence of the 

 white zebra ear-tip and the white asinine muzzle, as 

 well as in the more or less complete suppression ot 

 the stripes on the head and body ; and it is very 



