ANALOGOUS VARIATIONS. 143 



independently created species, that they have in varying 

 assumed some of the characters of the others. But the best 

 evidence of analogous variations is afforded by parts or 

 organs which are generally constant in character, but which 

 occasionally vary so as to resemble, in some degree, the 

 same part or organ in an allied species. 1 have collected a 

 long list of such cases ; but here, as before, I lie under the 

 great disadvantage of not being able to give them. I can 

 only repeat that such cases certainly occur, and seem to me 

 very remarkable. 



I will, however, give one curious and complex case, not 

 indeed as affecting any important character, but from occur- 

 ring in several species of the same genus, partly under 

 domestication and partly under nature. It is a case almost 

 certainly of reversion. The ass sometimes has very distinct 

 transverse bars on its legs, like those on the legs of the zebra. 

 It has been asserted that these are plainest in the foal, and, 

 from inquiries which I have made, I believe this to be true. 

 The stripe on the shoulder is sometimes double, and is very 

 variable in length and outline. A white ass, but not an 

 albino, has been described without either spinal or shoulder 

 stripe ; and these stripes are sometimes very obscure, or 

 actually quite lost, in dark-colored asses. The koulan of 

 Pallas is said to have been seen with a double shoulder- 

 stripe. Mr. Blyth has seen a specimen of the hemionus 

 with a distinct shoulder-stripe, though it properly has none; 

 and I have been informed by Colonel Poole that the foals of 

 this species are generally striped on the legs and faintly on 

 the shoulder. The quagga, though so plainly barred like a 

 zebra over the body, is without bars on the legs ; but Dr. 

 Gray has figured one specimen with very distinct zebra-like 

 bars on the hocks. 



With respect to the horse, I have collected cases in 

 England of the spinal stripe in horses of the most distinct 

 breeds and of all colors ; transverse bars on the legs are not 

 rare in duns, mouse-duns, and in one instance in a chestnut ; 

 a faint shoulder-stripe may sometimes be seen in duns, and 

 I have seen a trace in a bay horse. My son made a careful 

 examination and sketch for me of a dun Belgian cart-horse 

 with a double stripe on each shoulder and with leg-stripes. 

 I have myself seen a dun Devonshire pony, and a small dun 

 Welsh pony has been carefully described to me, both with 

 three parallel stripes on each shoulder. 



In the north-west part of India the Kattywar breed of 



i 



