the Genus Cercocebns, 279 



It was formerly lickl, even by authors familiar with C. fuli- 

 ginosus, that uniformity in the colour of the hair, or, to be 

 accurate, the absence of the subapical pale annuli so common 

 in the hairs of Cercopit/iecus, was characteristic of the genus 

 Cercocehufij yet in G, fulirjinosus there is a patch on the 

 crown of the head due to a broad yellowisli area on the hairs 

 of this region; and since the discovery of G. (jahritus, 

 G. agilis, and G. chrysogaster, speckled species all three, it 

 lias been tacitly admitted that the absence of the speckling 

 has only a specific importance. 



So far, tlien, as the colour of the hair and of the eyelids 

 is concornod, a gradation may be traced between the species 

 debarring generic or subgeneric sub livision even on the part 

 of those wishing to attach such weight to the particulars in 

 question; and it appears to me there is just as much or as 

 little reason for regarding the elongated whiskers of G. con- 

 gicus, or the brow-fringe of typical G. alhigena, or the long 

 and parted scalp-hairs of C. galeritus as supplying a basis 

 for subgenera as for considering the crown-tuft of C. alhigena 

 to have that value. The truth is, if the genus Gercocehus be 

 divided into subgenera at all, it may with as much justifica- 

 tion be split into three or four as into two. But since no 

 beneficial end is, in my opinion, served by giving subgeneric 

 names to isolated species or groups of species in so small and, 

 comparatively speaking, homogeneous a genus as Gercocehus^ 

 and useful names are thereby put out of court for other 

 nomenclatural purposes, I propose to regard Leptocehus as a 

 genuine synonym of Gercocehus *. 



1. The Sooty Mangabey. 

 Gercocehus fuUginosus^ Geoff. 

 Loc. Sierra Leone and Liberia. 



2. The White-crowned Mangabey. 

 Gercocehus lunulatuSy Teram. 



Cercocehus tethiops, Geoffroy, and of recent authors ; nee Simla athtops, 

 Linn. 



Cercocebus iuniilatus, Temniinck, Esquiss. Gain. p. .37 (1853) ; de Win- 

 ton, in Anderson's Mammals of Egypt, p. 15 (1902). 



* The pity of introducing new names like Leptocehus into a catalogue 

 compiled by an author who cannot claim an intimate acquaintance even 

 ■with all the genera, much less \\ath all the species he records, is well 

 exemplitied by the case under consideration ; for one of the alleged 

 species, Hayenbecki, figures in the subgenus Cercocebtis, and another, 

 agilis, in Leptocebus ; yet the two names were in all probability applied 

 to specimens only subspecifically distinct from each other. 



20* 



