118 CATALOGUE OF UNGULATES 



approximately equal size in both sexes. Muzzle haiiy ; no 

 face-glands or inguinal glands ; tail long and more or less 

 tufted at tip ; two pairs of teats ; lateral hoofs present ; feet 

 constructed on the same general type as in the Caprinm 

 (vol. i, p. 72) with glands in both pairs, which consist of a 

 thick-walled, elongated sac, discharging by an orifice situated 

 close to summit of interungual web, or (Addax) the whole 

 gland small and opening behind an excrescence from the top 

 of the web ; face-markings, which are present in the young, 

 of a gazelline type, when fully developed; these, and 

 apparently the foot-glands, indicating some kind of relation- 

 ship with the Antilopinm. Skull heavy, without supraorbital 

 pits or lachrymal depressions, and with small or no lachrymal 

 vacuities ; upper molars with tall subquadrangular crowns, 

 severally furnished with an accessory column on inner side, 

 and thus closely resembling those of the Bovince. 



The range of the group includes the more open districts 

 of Ethiopian Africa, together with Mesopotamia and Arabia. 



The three genera are distinguishable as follows : — 



A. Hoofs normal ; horns straight or sabre-like. 



a. Horns arising behind eye-sockets, and sloping 



backwards, at least at first, nearly in line of face . Oryx. 



b. Horns arising above eye-sockets nearly vertically. Hippotragiis. 



B. Hoofs low, flat, and broadly rounded in front ; horns 



forming a corkscrew-like spiral Addax. 



I. Genus ORYX. 



Oryx, Blainville, Bull. Soc. Pliilom. 1816, p. 75 ; Sclater and 

 Thomas, Book of Antelopes, vol. iv, p. 41, 1899 ; PococJc, Proc. 

 Zool. Soc. 1910, p. 907. 



Size medium or large. Horns, which are long, cylindrical, 

 and ridged in their basal halves, arising behind eye-sockets and 

 inclined backwards, for at least their basal portion, approxi- 

 mately in the plane of the face, after which they either 

 continue in the same line, diverging gradually, or sweep 

 backwards in a scimetar-like curve ; tail with a long, thick 

 terminal tuft ; direction of dorsal and nuchal hairs, in 

 advance of a whorl behind middle of back or on rump, 

 reversed. Skull relatively large, with small lachrymal 

 vacuities and the premaxillse reaching the nasals. 



