210 071 a neio Species of Mangahey. 



as Rotlischildi, wliicli these resemble in lengtli of whisker, 

 absence of frontal fringe, and, at least in the case of Ilnmlyni, 

 in the shape of the crest on the crown of the head. I do not, 

 liow^ever, think tliat such a conclusion is warranted by tlie 

 evidence; for, in the first place, the normal colour of the 

 eyes and the bilateral symmetry of tiie pattern formed by the 

 white patches in congicus and the black patches in JIamlyni 

 are not suggestive of albinism. Moreover, the absence of 

 black pigment under the skin of the face, hands, and feet in 

 some races of man and of chimpanzee and in some species 

 of macaques is opposed to the view that this defect is 

 necessarily or even probably indicative of albinos in the 

 higher Primates. Finally, although black is the prevalent 

 colour of the face in the genus Cercocehus, the face of 

 C.fuliginosus is often to a great extent flesh-coloured. As 

 for the yellowish-grey hue of the hairs in C. Ilamlyni, this 

 colour occurs too commonly in quadrumanous Primates, e. g. 

 in some species of langurs {iSemnoptthecus), the young of 

 some species of Colobus, and in some gibbons {Hylobates), to 

 be regarded as of pathological import. 



Another possible explanation of the coloration of these two 

 mangabeys is that C. albigena Rothschildi, or an allied form, 

 is an extremely variable animal, and that the types of 

 C. covgicus and C. Ilamlyni merely represent two of its 

 phases. The ascertained constancy in the coloration of other 

 species of this genus is, however, entirely opposed to such an 

 hy})Othesis. 



For the above-given reasons I think it desirable to describe 

 the monkey in question as the type of a new species. If the 

 opinion that its peculiarities are of specific value prove well 

 fonnded, its departure from the ordinary dusky style of 

 coloration prevalent in the genus is probably connected with 

 a difltrence of habitat demanding ditfereut procryptic attri- 

 butes. In looking for an explanation of this, one is reminded 

 of Dr. Gregory^s assertion that the white-mantled guerezas 

 [CoJvhus) of East Africa are concealed when sitting in the 

 trees by the harmonizing of their white plumes with masses 

 of white epiphytic lichens which clothe the branches. It is 

 possible that this new mangabey tinds concealment in the 

 same way. 



EXPLANATION OF PLATE VIL 



Cercocebus Hamlyni, sp. n. (Drawn from a photograph of the 

 living auimal.) 



