Zoological Society. 419 



orbital sinus, but have a fissure in the skull, and their incisors are 

 not widened at the summits. 



RlJPICAPRA. 



A minute suborbital fissure, but no fossa ; the masseteric ridge 

 ascending high before the orbit ; the auditory bulla very small and 

 compressed ; the basioccipital bone flat ; the incisors equal-sized, 

 vertical ; the molars without supplemental lobes. 



Horns slender, round, vertical, and hooked backwards at the tip. 



Hab. Europe. 



R. tragus. 



DlCRANOCERUS. 



No suborbital depression ; the fissure lengthened ; the nasal bones 

 widest posteriorly ; the orbit a little elevated above the line of the 

 face, and the masseteric ridge not rising before it ; the auditory bulla 

 moderate, compressed and angular ; the incisors equal-sized, sloping ; 

 the molars without supplemental lobes. 



Horns vertical, compressed, with a process on their anterior side, 

 and hooked backwards at the tip. 



Hab. North America. 



D. Americanus. 



Aplocerus. 



Horns round, vertical, gently curved backwards. 



Hab. North America. 



A. Americanus. 



I have seen no skull of this animal, but leave it for the present in 

 this location. 



I must forego all notice of the Ixalus probaton of Mr. Ogilby, as 

 there is no skull to be seen, and the horns in the only specimen 

 known are quite in a rudimentary condition. 



The genera next to be considered are the " Cervine Antelopes " of 

 Mr. Gray, exclusive of the genus Kolus, which I have rejected. With 

 the exception of the Nyl-Ghau and some of the Eleotragi, they are 

 the only members of the old genus Antilope that have well-developed 

 supplemental lobes in all the true molars ; they have always been 

 placed near together. 



iEGOCERUS. 



A small suborbital fissure, but no fossa; the masseteric ridge 

 ascending high before the orbit ; the auditory bulla moderate ; the 

 occipital portion of the skull much prolonged ; the basioccipital por- 

 tion widened, its two pairs of tubercles much developed, with a deep 

 groove between them ; the incisors gradually increasing in size to the 

 median pair, which are not expanded at their summits ; the molars 

 with largely-developed supplemental lobes. 



Horns rising immediately above the orbits, curved backwards, 

 annulated. 



Hab. Africa. 



2E. leucophcBus. AS. niger. 



27* 



