Skull, in proportion to the size of the animal, delicate, slender, and elongate. Muzzle slender, tapering, not laterally swollen between the premolars and the anteorbital fossa. Anteorbital fossæ of medium depth. Mesial notch of palate surpassing anteriorly the lateral ones by about half an inch, these latter comparatively deep and =V=-shaped. Horns long and tapering, lying back in or below the line of the nasal profile, rather bowed downwards terminally. Divergent, slender, evenly tapering, but little roughened at base; those of male and female almost precisely alike, except that the latter are slightly smaller. Length (♂) 6·4 inches; basal diameter going about 5 or 5½ times in the length. Dimensions:--♀. Height at shoulder 34 inches, ear 4, hind foot 13·5. Skull (♂): basal length 10·3 inches, greatest breadth 4·9, muzzle to orbit 6·5. _Hab._ West Coast of Africa, from Liberia to Angola. We commence our history of this numerous group of Antelopes, for which we adopt the term “Duiker” (_i.e._ “Diver”), originally given by the Boers of the Cape to _C. grimmi_, as a vernacular name, with two species readily distinguishable from the remainder by their greater size, but not apparently otherwise divergent in structure. These are the Yellow-backed Duiker and Jentink’s Duiker. The eminent Swedish naturalist, Adam Afzelius, a pupil of Linnæus, and subsequently editor of his master’s autobiography, resided for two years (1792–94) on the West Coast of Africa, as botanist to the Sierra Leone Company. Amongst numerous papers embracing the results of his researches on the West-African fauna and flora, he published in 1815, in the ‘Nova Acta’ of the Royal Society of Sciences of Upsala, a learned treatise on Antelopes generally, and specially upon those of Guinea. In the course of this memoir he described and figured for the first time the present species, calling it _Antilope silvicultrix_, as being the “Bush-Goat” of the colonists. Afzelius speaks of it as not uncommon in the hills round Sierra Leone, particularly in the districts adjoining the rivers Pongas and Quia. Here it is not met with among the rocks, but inhabits the lower tracts of the bush, either solitary or, in the rutting-season, in pairs, and occasionally in small herds. It hides itself in the bush by daytime, but comes out in the early morning to feed in the open spaces, where the hunters lie in wait for it. Its flesh is stated to be much esteemed as food, although it has a strong musky scent, particularly at certain seasons of the year.