DISTRIBUTION.--E. Africa; Mitola, at the mouth of the Osi and Tana rivers. HABITS.--This species was found living in the woods on the coast in small troops of from five to six in number. THE GUENONS. GENUS CERCOPITHECUS. _Cercopithecus_, Erxleben, Syst. Regn. Anim., p. 22 (1777). The genus _Cercopithecus_ includes a larger number of species than any other of the _Anthropoidea_. Its members are {42}characterised by their rather round head, slender but muscular bodies, narrow loins, and long hind limbs. Their tail is long, though shorter than in the genera next to be described, viz., the Langurs and the Guerezas. Their face is short, the muzzle less elongated, the cheek-pouches larger than in the Macaques. The nose is not prominent, and the nostrils are approximated, while whiskers are generally developed, as well as a longer or shorter beard. Their callosities are less extensive than in the Macaques. They have elongated hands with fingers united by a web at their bases; their thumbs, though distinct, being less developed in comparison than their great-toes. The fur is thick and soft, and in most of the species is ringed with differently and often brilliantly coloured bars. The _Cercopitheci_ have the skull depressed, presenting no very distinct brow, for its superciliary ridges are less prominent and angular, and their outer margin less projecting in comparison with those of the skulls in the genera already described. The orbits are considerably approximated. Their molar teeth are strongly cusped, and the posterior lower molar has only four cusps, and not five, as in the Macaques; but as in these animals, the two front cusps are united together by a transverse ridge, and the two hind ones are united together.