Commencing in 1846, Gray established his _Cephalophus dorsalis_ on a specimen in the British Museum, which had been brought to this country alive by Mr. Whitfield from Sierra Leone and had died in the Surrey Zoological Gardens. In 1850 he figured the same species in the ‘Knowsley Menagerie’ from a drawing made by Waterhouse Hawkins. This drawing was probably taken from living specimens in the Knowsley Collection, also procured by Whitfield, who was a collector employed by Lord Derby. In 1852 Dr. Gray seems to have come to the conclusion that the animal figured in the ‘Knowsley Menagerie’ was not the same as the true _Cephalophus dorsalis_ originally described from Mr. Whitfield’s specimen, and, accordingly, in his list of Ungulata Furcipeda in the British Museum, named the former _Cephalophus badius_, retaining the name _Cephalophus dorsalis_ for the latter. Dr. Gray, however, did not state exactly how the two species are to be distinguished, and he afterwards united them under one heading. The typical specimen of _C. breviceps_ was described when alive in the Zoological Gardens, and, as noticed by Gray himself, “assumed all the appearance, as it grew up, of _C. badius_” As recorded by Temminck in his ‘Esquisses Zoologiques sur la Côte de Guinée,’ the well-known Dutch collector Pel met with this Antelope in Ashantee and Sierra Leone, where he states that it is found, although somewhat rarely, in the littoral forests, showing itself only at night. Two other collectors from Holland, Büttikofer and Stampfli, obtained specimens of this species on the Junk River in Liberia, which were likewise transmitted to the Leyden Museum. Examples of this species in the British Museum were procured in Fantee by the native collector Aubinn; and we may therefore state confidently that the typical form of _C. dorsalis_ inhabits the whole coast-region of Western Africa from Liberia to the mouth of the Niger. When, however, we pass southwards of the delta of the Niger and arrive at the higher ground of the Cameroons the typical _C. dorsalis_ seems to be replaced by a slightly different local form, which Thomas in 1892 characterized as a subspecies, _C. dorsalis castaneus_. This Antelope is rather larger than the typical form and the ears are apparently rather larger. The chestnut superciliary stripe is indistinct, far less bright than in the typical form, and the general colour of the head is darker and duller. The typical specimen of this subspecies, which is in the collection of the British Museum, is a female obtained by Crossley in the Cameroons. Besides the colour-differences just mentioned the form of the skull, which is figured in the ‘Hand-list of Ruminants’ as that of _C. badius_ (_op. cit._ pl. xxx. fig. 1), is likewise peculiar. But further specimens and more information are necessary before we can decide whether it will be advisable to give the Cameroons animal the full rank of a species.