Vernacular Name:—_Blawe-bock_ of Dutch (_Le Vaillant_). Size much less than in the two following species; height at withers from 45 inches (♂ in Paris) to 40 inches (♀ in Vienna). General colour bluish grey. Forehead brown; upper lip and a patch in front of the eye lighter than the general colour, but there are none of the marked black and white contrasts so prominent in _H. equinus_. Ears not so long or so pointed as in _H. equinus_, and without black tufts at their tips. Mane on nape of neck short, inconspicuous, directed forward; throat-mane almost or quite absent. Belly dull whitish, not contrasted with the sides. Limbs with an inconspicuous darker line down their anterior surfaces. Tail-tuft greyish, but little darker than the general colour. Skull probably merely differing from that of _H. equinus_ by its smaller size, but, so far as is known, no museum possesses an example of it. Horns like those of _H. equinus_, but much smaller and more slender; perhaps rather longer in proportion to the size of the animal. Those of the Paris specimen (a male) measure 21½ inches in length round the curve and have 28 rings upon them. The pair in the British Museum are rather shorter. _Hab._ Cape Colony only. (Exterminated at the end of the last century.) The Blue-buck, like the Quagga (_Equus quagga_), belongs to the category of larger animals that have become extinct within the historic period. While the Square-lipped Rhinoceros (_Rhinoceros simus_) and the Mountain Zebra (_Equus zebra_) are still occasionally to be met with in one or two remote districts of South Africa, it would seem that the Blue-buck and the Quagga, as living creatures, have utterly perished from the face of the earth, and are only now represented by a few specimens in some of the principal museums of Europe. Although the “Blaauwe-bok” or “Blau-bok” was long known to early travellers at the Cape under its vernacular names, the great Russian naturalist Pallas was the first to register it definitely in the ‘Annals of Science.’ Under the name _Antilope leucophæa_ Pallas described it in 1766, in his ‘Miscellanea Zoologica,’ from a specimen in the Leyden Museum[1], and placed it as the first species of his genus _Antilope_. We have already, however (Book of Ant. III. p. 3), given the reasons why another species—the Black-buck of India—should be deemed to be the type of Pallas’s generic term _Antilope_, and in accordance with ordinary usage we employ Sundevall’s name _Hippotragus_ for the present species and its allies.