During the celebrated expedition of the naturalists of the Leyden Museum to Liberia in 1879 and following years Mr. Büttikofer first obtained perfect specimens of this Duiker on the St. Paul’s River. These were described by Dr. Jentink in the seventh volume of the ‘Notes from the Leyden Museum’ in 1885, and a figure was given of the skull. In the succeeding volume of the ‘Notes’ Dr. Jentink gave fuller particulars respecting this welcome rediscovery, and informed us that, as shown by the series of specimens collected by Mr. Büttikofer and his fellow travellers, this Antelope is not uncommon in certain parts of Liberia. The “Mountain-deer,” as the Americanized Liberians call it, does not occur in the coast-district, but is found in the mountainous terrain of the interior. Dr. Jentink gave coloured illustrations of the male, female, and young of this Antelope, together with representations of the skull of the adult male, the skull figured in the previous volume having been that of a female. In the second volume of his ‘Reisebilder aus Liberia,’ published in 1890, Mr. Büttikofer tells us that he first saw a living example of this species in the forest near Soforeh Place, and recognized it, with much delight, as the “Mountain-deer” of which he had heard so much spoken. Here he captured a young one alive, and subsequently found the skull of the mother, which was wounded but not obtained on that occasion. In his second expedition to Liberia, Mr. Büttikofer and his companions procured a full series of examples of this beautiful species. Mr. Büttikofer remarks that the weight of a full-grown example of this animal ranges from 40 to 50 lbs., and that a specially remarkable development in its structure is that of the hairs on the hind edge of the tarsus, which form a sort of brush. Our figure of this Antelope (Plate XX.) has been prepared by Mr. Smit from a stuffed specimen of an adult male in the British Museum obtained on the Du Queah River in Liberia during Mr. Büttikofer’s second expedition. In the same collection there is a skin of an adult female from the same locality, and the skeletons of both these animals. The flat skins which were the types of the specific terms “_doria_” of Ogilby and “_zebra_” of Gray are likewise in the National Collection. _August, 1895._ 31. THE BLACK DUIKER. CEPHALOPHUS NIGER, GRAY. [PLATE XIV. FIG. 1.]