_Cercocebus æthiops_, Geoffr. Cat. Méth. Primates, p. 25 (1851); Gray, List Mamm. Brit. Mus., p. 7; id., Cat. Monkeys Brit. Mus., p. 27 (1870); Schl., Mus. Pays-Bas, vii., p. 95 (1876). _Cercopithecus lunulatus_, Temm., Esquiss. Guin., p. 37 (1853). CHARACTERS.--This species is very similar to _C. collaris_, but differs in being slightly darker above, and in having a spot on {40}the back of the head, as well as a narrow streak down the back greyish-white. DISTRIBUTION.--West Africa. IV. THE GREY-CHEEKED MANGABEY. CERCOCEBUS ALBIGENA. _Presbytis albigena_, Gray, P. Z. S., 1850, p. 77, pl. xvi; Murie, P. Z. S., 1865, p. 740. _Cercocebus albigena_, Pucher., Rev. Zool., 1857, p. 241; Schl., Mus. Pays-Bas, vii., p. 97 (1876). _Cercocebus_ (_Semnocebus_) _albigena_, Gray, Cat. Monkeys Brit. Mus., p. 27 (1870). CHARACTERS.--Face nude, except for a few short hairs on the cheeks and lips; a tuft of long stiff hairs projecting over each eye; hair of the body elongated on the fore-quarter and arm; on the crown and nape the hair long and directed backwards, forming a crest; hands and feet short, tail long, thumb small, and great-toe large and broad; face black. General colour of the body black; cheeks, throat, a spot behind the ear, sides of the neck, shoulder, and front of the chest greyish; hairs on the face and over the eyes black; tail black; callosities black. A younger specimen, which died in 1865 in the Zoological Gardens in London, had the throat, sides of the neck and front of the chest, dirty-brown; hairs of the cheeks of the same colour, and some of them also black. DISTRIBUTION.--West Africa. V. THE BLACK MANGABEY. CERCOCEBUS ATERRIMUS. _Cercopithecus aterrimus_, Oudem. Zool. Gart., xxxi., p. 267 (1890). _Cercocebus aterrimus_, Scl., P. Z. S., 1893, p. 256 (note). {41}CHARACTERS.--Closely allied to _C. albigena_, but distinguished by its generally deep black colour, except on the shoulders and nape, which are blackish-brown or brownish-grey--the hair here being no longer than on the rest of the body; hairs on the cheeks, fine, velvety, and whitish; whiskers thick, greyish-brown; beard very sparse, whitish. DISTRIBUTION.--South-west Africa: Stanley Falls on the Congo. HABITS.--Unknown. VI. THE CRESTED MANGABEY. CERCOCEBUS GALERITUS. _Cercocebus galeritus_, Peters, M. B. Ak. Berl., 1879, p. 830, pls. i.B and iii. (Crania). CHARACTERS.--A flat crest of blackish-brown hair radiating from the top of the head all round and over the forehead; the entire upper surface covered with long loose fur, the hairs grey at their base, and higher up ringed with greyish-green and blackish-brown; the fore-arms, hands, feet, and the basal three-fourths of the tail blackish-brown; the sides of the head and the whole under surface yellowish; the inside of the limbs yellowish-grey; the hair of the terminal part of the tail lighter than the rest, and ringed with yellow; face, bluish-black.