834 On the Extinct Cats of America. [ December, 
_ to define that family, since I have found them to be wanting from 
various extinct genera. The only comprehensive definition which 
I can give is the following; 
Digits 5—4. Sectorial teeth well developed in both jaws ; not 
more than one true molar tooth in the upper, nor more than two true 
molar teeth in the lower jaw. Glenoid cavity grasping mandibular 
condyle anteriorly as well as posteriorly. 
Prof. Gill, who has devoted much attention to the definition of 
the families of the Mammalia, gives the following skeletal char- 
acters in his diagnoses of the Fede and of the three compre- 
hensive divisions within which he places it. “I. Skull with the 
paroccipital process applied closely to the auditory bulla; the 
mastoid process small or obsolete; external auditory meatus very 
short or imperfect. Div. A. Carotid canal minute and superficial 
or obsolete; condyloid foramen and foramen lacerumposticum 
debouching into a common fossa; glenoid foramen minute or 
null. Os peuis rudimentary. Subdiv. 1. Otic bulla divided by 
a septum into posterior and anterior chambers communicating by 
a narrow aperture (Flower). Subdiv. a. Skull with no alisphenoid 
canal.” All of the parts here mentioned I have found to be 
important in the definition of the natural divisions of the Car- 
nivora, excepting those derived from the paroccipital and mastoid 
processes. But their condition in the extinct Carnivora which 
have been hitherto arranged with the Fe/idg, and which resemble 
them very much in superficial characters, does not coincide with 
Prof. Gill’s definition. Thus in the various American genera 
which resemble Drepanodon, the carotid canal is distinct from 
the foramen lacerum posterius, and the condyloid foramen is also 
separated from it by quite a space. These are characters which 
belong to most of the Carnivora with five digits on all the feet. 
Further, the postglenoid and postparietal foramina are present, 
also characters of the lowest Carnivora, as the bears and certain 
extinct dogs. Then there is an alisphenoid canal, which is also 
found in bears, dogs and the cat-like Cryptoprocta, I cannot 
demonstrate that the otic bulla is divided as the above diagnosis 
requires, in any of the fossil species. I have verified the above 
characters on species of the following genera, of which I have =< 
preserved skulls; Archelurus, Nimravus, Dinictis, Pog onodon, 
Arrangement of the Families of Mammals, Smithson. Miscell, Coll., 230, 1877 
. 56. 
i Piace those of the base of the skull, 
