596 MANUAL OF ZOOLOGY. 



shed annually. The feet are cleft, but are furnished with 

 accessory hoofs placed on the back of the foot. 



The Cavicornia comprise the three families of the Antilopida, 

 Ovidcz, and Bovida. The Antelopes form an extremely large 

 section, with very many species. They are characterised by 

 their slender deer-like form, their long and slender legs, and 

 their simple cylindrical annulated or twisted horns, which are 

 sometimes confined to the males, but often occur in the females 

 as well (fig. 255). The Antelopes must on no account be con- 

 founded with the true Deer, to which they present many points of 

 similarity. The structure of the horns, however, is quite suffi- 

 cient to distinguish them. The Antelopes are further distin- 

 guished by rarely having a beard or dew-lap, and by the 

 general possession of "inguinal pores " and " lachrymal sinuses." 



Fig. 255. Head of the Koodoo {Strepsiceros Koodoo), 



The inguinal pores are the apertures of two involutions of the 

 integument of the groin, secreting a viscous substance, the use 

 of which is unknown. The lachrymal sinuses, or " tearpits," 

 have already been mentioned as occurring in the Cervida, and 

 are not found in any of the Cavicornia except the Antelopes. 

 Each consists of a sebaceous sac placed beneath the eye, and 

 secreting a yellowish waxy substance. The function of these 

 glands is uncertain, but it is probably sexual. The Antelopes 

 are especially numerous, both in individuals and in species, in 

 Africa, in which country they appear to take the place of the 

 true Deer (only one species of Deer being indigenous to 

 Africa). Amongst the better-known African species of Ante- 

 lopes .are the Springbok, Hartebeest, Gnu, Eland, and Gazelle. 

 The only European Antelope is the Chamois (Rupicccpra tra- 



