Mr. E. I. Pocock on the Equlda?. 307 



form a complete series of gradations may be found in which 

 the stripes gradually die away from the lioofs upwards, 

 ultimately leaving the belly, legs, and hind- quarters up to 

 the last flank-stripe unstriped. This suppression of stripes 

 on the limbs and belly is accompanied by an increase in the 

 number and forward extension of the shadow-stripes, the 

 consummation in both particulars being reached, so far as 

 existing types are concerned, in Burchell's quagga. In the 

 true, but now extinct, quagga the process was carried one 

 step further, the stripes being suppressed over the quarters, 

 and the shadow-stripes, at least apparently in some cases, 

 showing a great increase in development, the result being a 

 more uniform coloration of the fore part of the body and 

 head. It would be extremely interesting to discover why 

 these quaggas, as they passed from north to south in Africa, 

 found it advantageous to drop the stripes on tlieir limbs and 

 hind-quarters. The answer to this question could probably 

 be given by a careful study of the physical conditions under 

 wiiich each subspecies exists. 



4. Asiatic Wild Asses {? Equus, s. s.). — Certainly one 

 well-marked species, E. hennonus, with the subspecies 

 onager and hemippus. Possibly the Horses should be 

 here included, if E. Przevalskii be a valid species. 



As the quaggas are the most equine of the " zebras," so 

 the kiang is the most equine of the " asses." 



The question as to whether there is a genuine wild species 

 of true horse is still suhjudice. If the verdict be adverse, the 

 horse as a domesticated animal, artiticially modified to an 

 unknown extent, has no place in a system dealing with 

 existing species. Assuming for the moment that Prze- 

 walski's horse is not feral and not a hybrid, it must take its 

 place at the end of the series given above, probably, I think, 

 as a second species under section 4. 



In the specimens of this animal in the Zoological Gardens, 

 as in the original type, the hairs on the basal half of the tail 

 are much shorter than those at the end. The tail, in fact, 

 presents an intermediate stage between that of E. cabaUus and 

 of E. hemionus. Similarly, the mane of the kiang exhibited 

 in the Gardens is almost as much "equine" as "asinine" 

 in cliaracter. Moreover, considering tiie extent to which the 

 warts on the hind legs vary in size in domesticated horses, 

 it would be rash to give more than a specitic value to their 

 presence. 



