1904.] ON THE WILD ASS OF MONGOLIA. 431 



from the original one — namely, a fawn-coloured ai:iiinal with white 

 stripes. 



A similar effect is produced in the living animal, as exemplified 

 in York's picture, b}^ photography. 



I explain this by the supposition that the light fawn bands 

 between the dai-k bars of the Quagga, which evidently correspond 

 to the white stripes of Grant's Bonte- Quagga, had a less stable 

 pigment than the fawn of the rump ; and that in dead specimens 

 long exposed to the light these light areas (which were originally 

 of the same colour as the I'ump) faded to white, and also come out 

 white in photography ; wdiile in both cases the more stable fawn 

 of the rump (the tj^iical ass-colour) retained its original tint, oi- 

 approximately so. 



Whether the very curiously marked Quagga in the Vienna 

 Museum figured in the Society's ' Proceedings' for 1902 (i. p. 32) 

 indicates a distinct race I leave undecided, but, in any case, I 

 think that its coloration is due to the same cause as that above 

 mentioned. 



Reverting, in conclusion, once more to Dr. Major's observa- 

 tions, I have to notice the record of the presence of a vestige of 

 the pit for the face-gland in the skull of a young Ass. Apparently 

 a ti-ace of a similar feature exists in one of two young skulls of 

 that species in the collection of the Museum, so that its occurrence 

 would seem to be only occasional. Nevertheless, this suffices to 

 allow the statement that vestiges of the pit for the face-gland 

 are now known to occur in the skulls of thi-ee existing species 

 (including the Quagga in this category) of the Horse family, in 

 one of which it appears to be constant. 



2. Note on the Wild Ass of Mono-olia. 

 By E. Lydekker. 



[Received March 10, 1904.] 

 (Plates XXVII. & XXVIII.*) 



My attention has been directed by the President to a Wild 

 Ass in his Grace's collection at Wobui-n Abbey, which was 

 received with the Mongolian wild ponies, and is stated to have 

 been obtained as a colt in Kobdo, north-west of the Gobi Desert. 

 This animal, which is a male, is therefore about three years 

 old, and thus approaching its full stature. The sketch repro- 

 duced in the accompanying Plate XXVII. was made in June 1903, 

 at a time when the summer coat was at its best. 



In its make and actions — especially of starting when alarmed 

 with the head so elevated that the plane of the face is almost 

 horizontal — as well as in the general type of coloration, this Wild 

 Ass agrees essentially wdth the Kiang of Ladak and Tibet. Both 



* For explanation of the Plates, see p. 432. 



