Skull with small lachrymal vacuities and of the same general structure as in Hippotragus; but the bases of the horns, instead of rising vertically above the eyes and forming an elevated forehead as in that genus, project straight backwards, continuing the line of the face and lying in the same plane as the nasal bones.
Horns long, cylindrical, slender, straight, or with a gradual and gentle backward curvature, diverging at a very acute angle; ribbed in their basal half.
Female with horns as in the male.
Range of the Genus. Africa south of the Sahara, except in the west-coast woodland and Congo Basin; also Southern Arabia.
The five species of the genus here recognized may be arranged as follows:—
- a. Horns, when fully developed, crescentically recurved throughout. Neck and part of the shoulder to the base of the fore leg of a ruddy-brown hue and strongly contrasted with the yellowish-white tint of the body. 113. O. leucoryx.
- b. Horns normally straight or nearly so. Neck of the same colour as the body.
- a1. Size smaller (height about 3 ft. at the withers). Legs, with the exception of the pasterns, which are white, of a nearly uniform brown colour both outside and inside; body of a nearly uniform dirty white; no black spinal stripe, and only a faint throat-stripe; tips and edges of ears white; nearly the whole of the cheek beneath the eye covered with a large brown or blackish patch continuous with the ocular stripe; at most a faint brown stripe passing along the side above the belly; tail-tuft white at the base. 114. O. beatrix.
- b1. Size larger (height about 4 ft. at the withers). Colour of legs below knees and hocks pale dirty white, and lighter in tint than the body, though often patched with black in front; body and neck of a nearly uniform tawny hue, with a dark spinal stripe and a deep black throat-stripe; tips and adjacent edges of ears black; cheek below the eye of the same colour as the neck, bounded in front by the black ocular stripe and behind by a similar stripe running from near the base of the ear; a deep black stripe running along the side above the whitish belly; tail-tuft black.
- a2. Hairs on throat long, frequently forming a median tuft or beard; nasal patch black, united on both sides with the lower end of the ocular stripe and passing beneath the jaw, so as to form a complete black ring round the white muzzle; a black stripe above the knee on the fore leg, extending on the outer side almost to the shoulder; a large black patch on the rump; a black stripe above the belly on both sides continued on to the thigh, and there united with a large patch of the same colour, which covers the hind leg, both outside and inside, almost down to the hocks; a black patch or stripe on the front of the cannon-bone of the hind leg. 115. O. gazella.
- b2. Hairs on throat short, not forming a tuft or beard; nasal patch not meeting the ocular stripe, so that the muzzle is not circumscribed by a continuous black band; black stripe above the knee on the fore leg only extending about halfway up to the shoulder; hind-quarters of a nearly uniform tawny tint, without any black patches on the rump or thighs; lateral stripe above the belly not passing on to the thigh; hind legs without any black bands or stripes.
- a3. Black hairs on the ears not produced into a tuft; parting of the hairs on the dorsal median line lying far back upon the rump. 116. O. beisa.
- b3. Hairs on the ears produced into a long black tuft; parting of the hairs along the spine situated a little behind the middle of the back. 117. O. callotis.
THE BOOK OF ANTELOPES, Pl. LXXXI
Wolf del. Smit lith.
Hanhart imp