1907.] MONKEYS OF THE GENUS CERCOPITHECUS. 679 



The selection by Is. Geoffrey St. H.of callitricMis{-=sahaius)RS the 

 type of Cercopithectis rendered abortive Gray's action in assigning 

 the name Cercopithecus to other species unrelated to sahcetis. 

 Similarly W. L. Sclater's* selection of mona as the type of that 

 genus cannot be entertained, both for the above-given reason and 

 also because mona had been eliminated by Reichenbach as the 

 type of his section Mona. 



Although I have thus endeas'oured to show to what sections 

 of the genus Cercopithecus the various extant subgeneric names 

 must be applied, I have done so, not because I think the sections 

 have generic oi- subgeneric value, but simply because the names 

 have been proposed by earlier authors. The application of sub- 

 generic names to these sections is at present, I think, premature, 

 becavise they rest almost wholly upon colour- characters ; and if 

 the system be adopted with consistency, it will be necessary to 

 introduce additional names to emphasize the isolation of cei'tain 

 other sjoecies, such as G. neglectus, C. Vhoesti, and possibly 

 C. nigroviridis. 



The groups, moreover, are of unequal value. The diffei"ences, 

 for example, between C. petaurista and C. ascanius or C. signaius, 

 are, I think, of as much importance as those tha,t separate any of 

 the species referred to the three sections combined, named after 

 Qiictitans, leiicampyx, and albogularis — perhaps, indeed, of more 

 importance. 



One group, however, stands out from the rest and might 

 pei'haps with advantage be given fidl generic status. This is the 

 group name Erythrocelms, typified by patas. The living animals 

 differ markedly from other species, not only in colour, but in 

 form. They are slender Monkeys standing high on the legs, the 

 fore legs being particu.larly long as compai'ed with those of other 

 species, which are heavily built and low on the fore legs. A 

 compai'ison between them forcibly suggests the differences in 

 aspect between a Chitah and the larger species of Fells of about 

 the same size, such as a Puma or a Leopard ; and I suspect that 

 C. patas is more terrestrial and less arboreal than the other 

 members of the genus Gercopitliecus. 



I regret that lack of proper material has pi'evented me making- 

 use of skull-characters. To woi-k the genus from the ci-aniological 

 standpoint requires a series of skulls of both sexes at various ages 

 of development of each species, so that the extent of the variation 

 in individuals of the same age and of different ages may be 

 ascertained. The material for this is inadequate ; and since the 

 measurement and description of such skulls as I have seen would 

 have doubled my work and inordinately added to the length of this 

 paper, without yielding commensurate taxonomic results, I have 

 been compelled to abandon, at all events for the present, all 

 consideration of cranial characters. 



One great systematic difiiculty that I have had to face, and in 



* 'Fauna of 8. Africa': Mammals, i. p. 5 (1900). St e also Palmer, ' Catalog-uo 

 of the Genera of Mammalia' (1904). 



