( 139 ) 



Clearly, then, Gray's pluto should be described as having a violet face, iu which 

 respect it agrees with leucampyx. In spite of the marked difference of the figure 

 of the latter from the type skin oi plido, I am of opinion, on this and other grounds, 

 that the identification of the two is jirobably correct. 



2. Arabian Baboon— Papio hamadryas arabicus. 



A short while ago Mr. 0. Thomas {Proc. Zool. Soc. Zrt»r/o«, IsOii, p. 929 ; 

 19U0, p. 96) described the skull and skin of a fi'iiiaU baboon obtained iu the 

 mountains about sixty miles north-west of Aden, as a new species under the name 

 of Papio arabicus. The chief ground for distinguishing this animal from 

 P. kamadn/as (to which it is sujiposed to be closely related) is the much smaller 

 proportionate size of the skull and cheek-bones as compared with those of a male 

 of the typical Abyssinian hamadryas {^female skull of the latter l^eing at the time 

 unavailable for comparison). In the course of the description it is mentioned that 

 the presumed new species is in all probability quite distinct from the representatives 

 of hamadryas which are well known to occur in the immediate neighbourhood of 

 Aden. It is further suggested that these latter, in place of being indigenous, may 

 have been imported from the Somali coast, as the native traders are known to 

 constantly carry baboons in their boats. 



Among the collection now uuder consideration are included a remarkably fine 

 pair {male and female) of hamadryad baboons, which are stated to have been caught^ 

 in the neighbourhood of Aden, and not imported from the opposite coast. Both are 

 fully adult, this being made manifest in the case of the male by his enormous tusks 

 and the extremely light colour of the profuse mantle of long hair on the shoulders 

 and of the cheek-tufts. In this species it appears, indeed, that in early life the 

 tnales (like the females at all ages) are dark olive-brown, the pale ashy colour of 

 the mantle and cheek-tufts not being assumed till mature age is attained. 



Compared, however, with a male skin of the Abyssinian form in the British 

 Museum collected by Siippell, which is still in the olive-brown pelage, the male 

 in the Zoological Gardens appears considerably smaller ; and I should say that 

 this animal is about one-third smaller than full-grown Abyssinian specimens. 

 Moreover, a stufled male presented to the British Museum by the late Dr. J. 

 Anderson, which is said to be from Aden, and is in the pale ashy j^elage of the 

 adult, is quite small compared to the Abyssinian animal. 



Again, the tyye/emale skin of arabicus, so far as my eye can recall, appears 

 identical with the living Aden female in the Gardens. 



Whether there is any difierence in the colour or length of the hair between 

 Abyssinian and Aden males, I have no personal knowledge. Mr. Rothschild tells 

 me, however, that in the latter the colour is a rather darker grey, while the face- 

 tufts are twice as long. In the photographs of African specimens taken during 

 Lord Delamere's expedition these tufts seem to be very large, so that further 

 information on this point is desirable before anything definite can be said. 



Confining ourselves, however, to the matter of size, and assuming the reputed 

 origin of Mr. Eothschild's specimens to be correct, there would seem to be evidence 

 that the Aden representative of P. hamadryas is considerably inferior in size to the 

 typical Abyssinian form ; and, if this be so, it is probably identical with P. arabicus, 

 which is undoubtedly indigenous to Arabia. The specimens in the Gardens are, 

 however, so like the Abyssinian form that, in spite of the isolation and consequent 

 absence of intergradation between the Arabian and Abyssinian animals, I am of 



