Skull proportionally long, its frontal region very convex upwards, the large horn-cores rising almost vertically above the posterior half of the orbits. Lachrymal fissures almost or quite obsolete. No anteorbital fossa. Premaxillæ not reaching to the nasals. Horns medium or long, slightly but evenly divergent, nearly vertical basally, strongly curved backwards above; heavily ringed. _Female_ with horns similar to those of the male, but shorter, slenderer, and much smoother. _Range of the Genus._ Africa south of the Sahara, but not occurring in the great Congo Forest. Of this genus, which contains some of the handsomest Antelopes in existence, we recognize three species, one of them (alas!) now extinct. The widely distributed Roan Antelope may be provisionally separated into four local subspecies, which require further elucidation. A. General colour greyish or pale brown. Horns not or but little longer than the head. _a._ Size smaller. Face without black markings. 110. _H. leucophæus._ _b._ Size larger. Face with strongly contrasted black and white markings. 111. _H. equinus._[4] _a1_. General colour greyish; ears shorter. (S. Africa.) Subsp. _typica_. _b1_. General colour pale rufous; ears shorter. (E. Africa.) Subsp. _rufo_-_pallida_. _c1_. General colour browner; ears longer. (N.E. Africa.) Subsp. _bakeri_. _d1_. General colour more fulvous; ears still longer. (W. Africa.) Subsp. _gambiana_. B. General colour black. Horns much longer than the head. 112. _H. niger_. [Illlustration: THE BOOK OF ANTELOPES, PL. LXXVI. _Wolf del. J. Smit lith._ _Hanhart imp._ The Blue-Buck, ♂ and ♀. HIPPOTRAGUS LEUCOPHÆUS. _Published by R. H. Porter._ ] 110. THE BLUE-BUCK. HIPPOTRAGUS LEUCOPHÆUS (Pall.). [PLATE LXXVI.] _Blue Antelope_, =Pennant=, Quadr. p. 66 (1781). _La Gazelle Tzeiran_, =Buff.= Hist. Nat. Suppl. vi. p. 168, pl. xx. (1782). _Blaauw-bok_, =Sparrm.= Voy. to Cape (Engl. transl.), ii. p. 219 (1786). _Blawe Bock_, =Le Vaill.= Voy. à l’int. de l’Afrique, i. p. 58 (1790).