Cercocebus aterrimus and Oercocebus albigena. 529 



in question inhabits the country south of the great river. It 

 is specifically distinct from Gercocehus albigena. 



It is necessary now to settle the question of the local races 

 of Gercocehus albigena itself. Lydekker (1900) and Pocock 

 (1806) have considered the subject, but both have arrived at 

 wrong conclusions, principally as they mixed up C. aterrimus 

 with this species. 



The type of G. albigena, Gray, is in the British Museum. 

 It is a young animal, stated to be from " West Africa," and 

 comes, as I suppose, from somewhere on the Lower Congo. 

 A second specimen collected by Du Chaillu fully agrees 

 with it. 



They are both black, with a sooty brown mane on the 

 shoulders, the region between the shoulders being darker. 

 The occipital crest is black for its greater part, and only quite 

 behind is it sooty brown. The arms are black, the cheeks 

 greyish ; the thighs are sooty brown, only slightly darker 

 than the mane, the feet black. This form must stand as 

 Cercocebus albigena albigena, Gray. It inhabits the Lower 

 Congo region. 



The second set of specimens comes from Eastern Africa : 

 Uganda (2 specimens) ; Mpanga Forest (2 specimens) ; Lake 

 Tanganyika (type of C. a. johnstoni, Lyd.) ; Lake Mweru 

 (type of C. jamrachi, Poc). They are very similar to the 

 preceding ones, but the mane is somewhat lighter, the region 

 between the shoulders not darker, and there are more brown 

 hairs in the occipital crest. The thighs are black or brownish 

 black. One specimen from Lake Tanganyika, the type of 

 C. a. johnstoni, does not well agree with this description, the 

 coat being much shorter and the mane very dark. This latter 

 feature, as Prof. O. Neumann pointed out, is due to the y r oulh 

 of the specimen ; a young animal from the Welle Kiver 

 iustifies this view. The condition of the fur most probably is 

 the consequence of the animal having been kept in cap- 

 tivity. The type of G. jamrachi, Pucock, has a distinct 

 brow-fringe, a mane, and an occipital crest, the condition of 

 the fur being quite as in G. albigena. It is white all over, 

 with pinkish naked parts and, curiously enough, brown eyes 

 like all the albinistic forms of G. aterrimus I have seen. I 

 have no doubt in referring it to C. albigena, and, as it conies 

 from the eastern part of its range, to subspecies johnstoni, 

 Lyd. Cercocebus albigena johnstoni inhabits the Upper Congo 

 and the Lake District from Uganda in the north to Lake 

 Mweru in the south. 



Ann. d) Mag. N. Hist. Ser. 8. Vol. v. 36 



