SPECIFIC CHARACTERS HIGHLY VARIABLE 173 



tant parts of the world, should all have been crossed with 

 one supposed aboriginal stock. 



Now let us turn to the effects of crossing the several spe- 

 cies of the horse-genus. Rollin asserts, that the common 

 mule from the ass and horse is particularly apt to have bars 

 on its legs; according to Mr. Gosse, in certain parts of the 

 United States about nine out of ten mules have striped legs. 

 I once saw a mule with its legs so much striped that any one 

 might have thought that it was a hybrid-zebra; and Mr. 

 W. C. Martin, in his excellent treatise on the horse, has 

 given a figure of a similar mule. In four coloured drawings, 

 which I have seen, of hybrids between the ass and zebra, the 

 legs were much more plainly barred than the rest of the 

 body ; and in one of them there was a double shoulder-stripe. 

 In Lord Morton's famous hybrid, from a chestnut mare and 

 male quagga, the hybrid, and even the pure offspring subse- 

 quently produced from the same mare by a black Arabian 

 sire, were much more plainly barred across the legs than is 

 even the pure quagga. Lastly, and this is another most re- 

 markable case, a hybrid has been figured by Dr. Gray (and 

 he informs me that he knows of a second case) from the ass 

 and the hemionus; and this hybrid, though the ass only occa- 

 sionally has stripes on his legs and the hemionus has none 

 and has not even a shoulder-stripe, nevertheless had all four 

 legs barred, and had three short shoulder-stripes, like those 

 on the dun Devonshire and Welsh ponies, and even had some 

 zebra-like stripes on the sides of its face. With respect to 

 this last fact, I was so convinced that not even a stripe of 

 colour appears from what is commonly called chance, that I 

 was led solely from the occurrence of the face-stripes on 

 this hybrid from the ass and hemionus to ask Colonel Poole 

 whether such face-stripes ever occurred in the eminently 

 striped Kattywar breed of horses, and was, as we have seen, 

 answered in the affirmative. 



What now are we to say to these several facts? We see 

 several distinct species of the horse-genus becoming, by 

 simple variation, striped on the legs like a zebra, or striped 

 on the shoulders like an ass. In the horse we see this ten- 

 dency strong whenever a dun tint appears — a tint which ap- 

 proaches to that of the general colouring of the other species 



