^Egocerus. 
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, 
annulate d. 
Hab. Africa. 
JE. leucophceus. 2E. niger. 
Oryx. 
A suborbital fissure, but no fossa, the masseteric ridge not extend¬ 
ing high ; the auditory bulla large and compressed; the basioccipital 
bone with its tubercles well-developed; the molars with supplemental 
lobes. 
Horns straight or gently curved, annulated, placed in a line with 
the face. 
Hab. Africa. 
O. gazella. O. leucoryx. 
It is only in Mr. Cumming’s collection that I have seen entire skulls 
of the Gemsbok, and the lower jaw being absent, I could not ascer¬ 
tain the character of the incisors. The skull of the Leucoryx I have 
not seen. 
Addax. 
A small suborbital fissure, but no fossa; the masseteric ridge 
ascending before the orbit; the auditory bulla large, prominent, and 
compressed ; the basioccipital bone with its anterior pair of tubercles 
slightly, the posterior well, developed ; the median incisors expanded 
at their summits; the molars with supplemental lobes. 
Horns nearly in a line with the face, annulated, spirally twisted. 
Hab. Africa. 
A. naso-maculata. I have seen but one skull of this animal, and 
that is a young one, in the Society’s collection, still reta inin g the 
whole of its milk dentition. 
Before proceeding to the Sheep and Goats, the Nyl-Ghau requires 
to be introduced. It seems to stand alone, not having a decided 
affinity for any other genus. 
PORTAX. 
The nasal opening rather small, with the nasal bones small and 
narrow; a minute suborbital fissure ; no fossa, but a smooth line 
upon the lacrymal bone; the masseteric ridge not extending high; 
the auditory bulla moderate, bulbous, compressed ; the basioccipital 
