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ON A EEMAEKABLE NEW SPECIES OF MANGABEY-LIKE 

 MONKEY {CEBCOCEBUS CHRYSOGASTEH). 



By R. LYDEKKER. 



(Plate III.) 



THIS monkey was sent from the Upper Congo to Mr. Carl Hagenbeck, of 

 Hamburg, who forwarded it to London. 



From the Impossibility of examining the skull and dentition, the generic 

 position of this interesting species cannot be accurately determined, but it appears 

 to agree so closely in general characters with the '• Mangabeys " that it may safely 

 be placed for the present in the genus Cercocebits. It agrees with the other 

 members of this genus in the bare upper eyelids (these both in this species and 

 in the remaining ones of the genus should be described as flesh-coloured rather 

 than white). It also agrees with the Blangabeys approximately in general form, 

 relative length of tail, in the manner of carrying the latter over the back, and in 

 its screaming cry when disturbed. It differs, however, from the ordinarily accepted 

 definition of the genus Cercoccbus in that the hairs of the crown of the head 

 are distinctly annnlated with yellow, as are to a lesser degree those of the back. 

 But as a similar feature occurs in an undoubted Cercocebus now in the Zoological 

 Society's Gardens (referred tentatively to C. fidiginosus *), it is e's-ident that the 

 absence of annulation can no longer be regarded as cliaracteristic of the genus. 

 The specimen is not fully adult, so that the proper size of the form to which it 

 belongs cannot be determined ; but it evidently indicates a small monkey of the 

 approximate dimensions of an ordinary Cercocebus. 



Having the bare upper eyelids and general form of Cercocebus, this specimen 

 may be described as follows : — 



Hair of crown of head light olive-coloured, with a speckled aj)pearance, due to 

 the presence of dark and yellow rings on the individual hairs. Fur of back of the 

 same general tint, but the speckling becoming less defined on the lateral and hinder 

 portions of the back, and finally disappearing on the flanks and outer sides of 

 limbs and tail, which tend to slate-grey in colour. Paws darker. Face brownish, 

 whiskers somewhat lighter coloured than crown of head. Under-parts from chin 

 to root of tail bright orange. Inner surface of limbs rather paler than outer 

 surface. 



The bright orange nnder-surface of this monkey distinguishes it from all other 

 species of Cercocebus, as well as all species of Cercopithecus, and suggested at 

 once the name of " ckri/sogaster." 



No other Mangabey has any approach to the same ventral coloration. In 

 young .specimens of the " Drill " and " Mandrill '" the chin-tuft is of the same orange 



* Having examined this specimen, I am o£ opinion that it is rather a very young female of the new- 

 species Cercocebus chrysoijasti-r t\an ot C./ii!i^iiiosus.—\\'AhTER Rothschild. 



