4 
420 Mr. R. I. Pocock on some of the Cranial 
The character usually cited as distinctive of Acinonya« is 
the incomplete sheathing of the claws, owing to longer or 
weaker retractile ligaments than are found in other forms of 
Felidse. To this have been added the relatively longer limbs 
and thinner body and one or two cranial features, such as the 
absence of the inner lobe on the upper carnassial and the 
smallness of the anteorbital foramen. But since the cranial 
characters mentioned are not distinctive, and the thinness of 
the body and length of limb are approximately equalled in 
some of the typical Felidz, e. g., the serval (F. serval), and 
the characters derived from the feet are very imperfectly 
Fig. 1. 
Jaws of Acinonyx jubatus, nat. size, showing particularly the obliteration 
of the postcanine space when the mouth is closed. 
described and understood, it may be useful to state what are 
the actual differences between Aciénonyx and other members 
of the family. 
Skull.—Neither of the cranial characters quoted above as 
alleged to be distinctive of Acinonyx can be granted that 
claim. The skull, nevertheless, presents a combination of 
features quite important enough, in my opinion, to justify 
the admission of the genus without taking the feet or other 
characters into consideration. 
The skull is short, high, and dome-shaped, the facial and 
cranial regions being tolerably evenly and steeply sloped 
from the interorbital region of the frontals. The face is not 
