224 External Characters of Ruminant Artiodactyla. 



structure of the penis, the presence of four mammse, the 

 absence of inguinal glands, and the presence on all four 

 feet of flask-shaped pedal glands with narrow exit passage 

 and small circular orifice just behind the summit of the 

 interungual web. 



Fiar. 5. 







B 



"•> 



A. Muzzle and rhinarium of Hippotragus niger from the front. X 5. 



B. The same from above. 



Setting Addax aside, the genera discussed in this paper 

 may be distinguished as follows : — 



a. Rhinarium sculptured, with distinct philtrum reach- 

 ing lower edge of upper lip ; upper rim of dilated 

 nostrils swollen ; horns rising erect from head . . Hippotragus. 

 a'. "Rhinarium smooth, without philtrum, upper lip 

 entire ; upper rim of narrow nostrils not swollen ; 

 horns inclined backwards in the plane of the 

 forehead. 

 b. Preorbital gland present as a thickened pad of skin 

 like that of Hippotragus ; rhinarium shallow ; 



horns curved JEgoryx. 



b' . Preorbital gland absent; rhinarium deeper; 



horns straight Oryx. 



