( 594 ) 



of sexual eolonr variations in this grou]) of monkeys (which might also bo taken as 

 an argument against {\xe female belonging to C. chri/sogiiitter), lint the case of the 

 proboscis monkey shows that very marked sexual Jiftereuces may occur iu the form 

 of some monkeys. It might also be urgeil that both the male and female under 

 consideration are hybrids between Cereocebus and Cercopithectts ; but in the absence 

 of any direct evidence that such is the case, it seems inadvisable to entertain this 

 hypothesis. 



Putting, then, on one side both the supposition of hybridism and the female 

 specimen, it seems, so far as we may judge from au immature animal, that the male 

 specimen cannot be assigned to any named species of Cereocebus. And since it 

 appears to be intimately connected with the more typical members of that genus by 

 the above-mentioned female, it may be provisionally regarded as the representative 

 of a new species, which maybe appropriately named C. hagenbecki, after Mr. C. 

 Hagenbeck, of Hamburg. 



It must remain for post-mortem examination to determine whether this racte 

 differs from typical species of Cereocebus in the form of the last lower molar ; and 

 if so, whether it should be regarded as representing a genus, or subgenus, connecting 

 the latter with Cercopithecus. In the character of its fur it is certainly intermediate 

 between the two ; and by the black upper eyelid it is differentiated from typical 

 Cercocebi. But, on the other hand, it should be remembered that in the 

 undetermined female we have the same mingling of mangabey and guennn hair 

 associated with a mangabey eyelid, while in C'. clirygogaster we find a completely 

 gueuon pelage correlated with the mangabey e3-elid. 



The female, I am informed by Mr. Sclater, was presented to the Society by the 

 Rev. A. Christopher, and came from the Mobangi River, about three hundred miles 

 above its junction with the Congo. The 7nale was brought down the latter river. 



Turning to the second specimen (see vol. viii. PI. I. fig. 2), we find that this 

 is likewise an immature male, which is specially characterised by its almost wholly 

 black colour, and the presence of a backwardly-directed crest of long hair rnnning 

 from the centre of the forehead to the occiput and terminating iu a point about tlie 

 vertex of the head. This crest gives to the animal an appearance which cannot 

 be mistaken when once seen. In colour the animal is almost completely black : 

 but the whiskers, which are large and spreading, show a slaty tinge, and there is 

 pnibably some tendency to slaty on the shoulders and najie, although this is diliicnlt 

 to determine in the living animal. The upjier eyelids are as dark-coloured as the 

 rest of the face ; but the callosities are of a bright orange-red. The tail, which is 

 nearly bare below, is slightly tufted at the end, and the hair generally is somewhat 

 long and coarse, being more elongjited on the nape and shoulders than elsewhere. 



With the exception of the crest on the head and the black upper eyelids, the 

 animal presents all the features mentioned under the heading of the preceding form 

 as distinctive of Cereocebus from CercopitAecus. 



In its general characteristic this monkey accords with Cereocebus albigena 

 (Gray *), from West Africa, of which the type skin is in the British Museum 

 (No. 51. 1. 19. 30) ; both specimens showing the general black colour, the cranial 

 crest of hair, and the black upjjer eyelid. In regard to the last-mentioned feature, 

 it may be observed that Gray, in his British Museum Catalogue of Monlte>/s, 

 Lemurs, and Fruit-eating Jiuts,] gave white eyelids as characteristic of all species 



• Proc. Zool. Soc. Loiul. 185U. \i. 77. pi xvi. I^Prrsbytcs). f 1S70. p. 26. 



