Size medium. General colour bright orange, becoming rather more rufous on the hindquarters. Nose brown, but otherwise the face is of the same colour as the body. Nape and sides of neck brown or blackish, but the hairs here so thin and short that the skin shows through and the general colour is but little affected. Hinder back with a marked black central dorsal streak, commencing vaguely at the withers, becoming narrower and more sharply defined posteriorly, and running on to the tail. Limbs dull yellowish, except on the phalanges, where they are brown or black. Horns in the direct line of the nasal profile; those of male about four inches long, conical, slightly incurved, much broadened basally, their greatest basal diameter going 2½ or 3 times in their length. Female about an inch and a half in length, conical, smooth, broad at base, pointed terminally, their length not twice their basal diameter. Skull with a very considerable convexity in the frontal region. Anteorbital fossæ shallow. Posterior palate with the three notches, median and two lateral, all at about the same level. Dimensions:--♂. Height at withers 22 inches, ear 3, hind foot 9·4. Skull (♂, not fully adult): basal length 7·2 inches, greatest breadth 3·5, muzzle to orbit 4·4. _Hab._ Coast of West Africa, from Liberia to the Cameroons. Ogilby’s Duiker, which we now proceed to consider, is closely allied to the last species, and like it is of a generally rufous colour with a black dorsal stripe, but it is immediately distinguishable by its pale yellowish face and flanks. It was first described by Waterhouse, as long ago as 1838, from specimens presented to the Zoological Society’s Museum by Mr. George Knapp, who had received them from the island of Fernando Po, and was named after William Ogilby, formerly Secretary to the Society and a great authority upon the Ruminant Mammals. When the Zoological Society’s Museum was broken up the typical specimen passed into the British Museum, where it now is. About ten years afterwards Ogilby’s Duiker was figured by Fraser in his ‘Zoologia Typica,’ probably from the typical specimen. Fraser, who had visited Fernando Po himself, states that this Antelope is extremely common in that island and is much esteemed by the natives as an article of food. In his conjecture that its range “is confined to that island,” he was no doubt in error, as we have several trustworthy notices of its occurrence elsewhere. Specimens of the present species are recorded by Dr. Jentink as having been procured on the Du Queah and Farmington Rivers in Liberia by Büttikofer and Stampfli. These are in the Leyden Museum, as is also a female specimen from Ashantee. In his ‘Reisebilder aus Liberia’ Büttikofer tells us that the present species is common in the Liberian forests.