208 UNGULATA order vii 



from the North American selenodont artiodactyls. The previous subdivision 

 of the group into the Antelopes, Ovines and Bovines is not fully justified 

 by the known phylogeny. There is good reason in favour of dividing the 

 extensive tribe of Antelopes into two groups, differing as to characters of 

 the dentition, and to unite these groups with the Ovines and Bovines. This 

 arrangement will then permit us to recognise two large subfamilies, namely : 

 (1) the Aegodontia, characterised by hypsodont molars, the upper ones of 

 which are longer than broad; and (2) the Boodontia, with cerviform molars, 

 the upper ones being quadrate in outline. 



The earliest fossil Cavicornia are from the Miocene of Europe. They are 

 deer-like forms possibly having sprung from Dremotherium, and representing 

 the ancestral Boodontia. These latter attain a great variety of forms in the 

 Pliocene, and are represented in the Pleistocene of North America. During 

 the Pleistocene an immigration took place from Asia into Europe and Africa. 

 The evolution of the group appears to have progressed independently in 

 North America, at least as regards the race of musk-oxen. 



Subfamily 1. Aegodontia Schlosser. 



Skull almost always arched, frequently with lachrymal fossa or ethmoidal vacuity, 

 or with both, or sometimes with a cleft close to the nasal hones. Parietal hones 

 always entering largely into the formation of the cranial surface. Cranial axis usually 

 bent. Air-cavities generally restricted to the base of the horns, rarely occupying 

 the entire osseous appendages. Horns seldom straight and cylindrical, usually 

 laterally compressed and directed backward, rarely spiral or turned outward, always 

 arising just above the orbits. Molars chiefly hypsodont, seldom with weak basal pillar, 

 as a rule without vertical costae on the external or internal tubercles. Premolars and 

 molars always with enamel smooth. 



The Aegodontia include the Neotraginae, Gazellinae (Antilopinae of Sclater), 

 Enpricaprinae, Ovicaprinae and Ovibovinae, the first two of which were formerly 

 classed with antelopes in the widest sense. In the structure of the teeth, 

 however, they differ so essentially from the latter forms that their separation 

 seems absolutely unavoidable. On the other hand they exhibit such close 

 relationship to the Ovicaprinae that it is probable the three groups have had a 

 common origin. The North American Antilocapridae may be regarded as the 

 common ancestral stock, the teeth of which have smooth enamel. In the 

 Ovicaprinae and Gazellinae {Antilopinae of Sclater) the relationship is further 

 emphasised by the fact that both possess relatively long splint bones. These, 

 howevei', are represented in the former group by scarcely more than the 

 fifth metacarpal. The other Cavicornia exhibit the same manner of reduction 

 in the lateral digits as in the deer. Among gazelles reduction of the 

 premolars frequently takes place. 



Group 1. Neotraginae Sclater and Thomas. 



Skull slightly arched, with lachrymal fossa, without ethmoidal vacuity. Horns 

 cylindrical, inclined backward, tips directed forward. Teeth brachyodont. 



Neotragus, Oreotragus, Baphiceros, Madoqua and Ourebia. Eecent ; Africa. 



