CHARACTERS.--Similar to _C. grayi_, but differs in the yellow forehead being interrupted in the middle by only a few black hairs, and not by a streak; the whiskers paler; the back part of the head, the fore part of the back, and the sides grizzled, the hairs being black, ringed with white; while down the middle of the back to the base of the tail runs a broad black stripe. DISTRIBUTION.--Fernando Po. XXXV. THE BLACK-FOOTED GUENON. CERCOPITHECUS NIGRIPES. _Cercopithecus nigripes_, Du Chaillu, Pr. Bost. N. H. Soc., vii., p. 360 (1860); Gray, P. Z. S., 1868, p. 182; Scl., P. Z. S., 1893, p. 254. _Cercopithecus erxlebenii_, var. _nigripes_, Gray, Cat. Monkeys Brit. Mus., p. 23 (1870). _Cercopithecus pogonias_, Schlegel, Mus. Pays-Bas, vii., p. 182 (1876). CHARACTERS.--Very similar to _C. pogonias_, but differs in being darker, and in having the dorsal stripe wider and more diffused lower down. It is probably only a variety of the preceding. DISTRIBUTION.--Gaboon, where it was discovered by Du Chaillu. {79}XXXVI. WOLF'S GUENON. CERCOPITHECUS WOLFI. _Cercopithecus wolfi_, Meyer, Notes, Leyden Mus., xiii., p. 63 (1891); id., P. Z. S., 1894, p. 83, pl. vii.; Sclater, P. Z. S, 1893, p. 258. CHARACTERS.--Face, except the lips, which are flesh-colour, and the temples, greyish-black; a yellowish-white bar across the forehead from ear to ear; whiskers greyish-yellow; ear-tufts reddish-brown; upper surface dark slate-grey; sides blue-grey, the hairs barred with several pale rings, and tipped with black; dorsal stripe, narrowing towards the tail, olive-yellowish, brighter on the crown, and brownish-yellow towards the tail; basal half of the tail above, ashy-grey, below white; an orange-yellow patch on the sides; chin, sides of neck, under surface of body and inner side of limbs white; belly washed slightly with orange; shoulders and outer aspect of the fore-limb, black--the hairs ringed with grey; on the hinder edge of the fore-arms an ochre-coloured stripe; outer side of thighs and legs bright red-brown, becoming orange on their anterior and posterior internal margin. Length of body, 18¼ inches; of tail, 24 inches. DISTRIBUTION.--West Africa: the exact locality is unknown. VI. CERCOPITHECI BARBATI. The members of this group are distinguished by possessing a beard and a frontal crest. XXXVII. THE DIANA GUENON. CERCOPITHECUS DIANA. _Simia diana_, Linn., Syst. Nat., i., p. 38 (1766). {80}_Cercopithecus diana_, Erxleb., Syst. Regne An., p. 30 (1777); Desmar., Mamm., p. 60 (1820); Martin, Mammif. An., p. 523 (1841); Geoffr., Dict. Hist. Nat., iii., p. 304 (1849); Wagner in Schreb. Säugeth. Suppl., v., p. 48 (1855); Gray, Cat. Monkeys Brit. Mus., p. 22 (1870; pt.); Schl., Mus. Pays-Bas, vii., p. 92 (1876; pt.); Jentink, Notes, Leyd. Mus., x., p. 12; Sclater, P. Z. S., 1893, p. 254. _Cercopithecus diana_, var. _ignita_, Gray, Cat. Monkeys Brit. Mus., p. 22 (1870).