[Extracted from the Proceedings of the Academy of Natural Sciences of Philadelphia, 
July 8, 1879.] 
ON THE GENERA OF FELIDE AND CANIDE. 
BY E. D. COPE. 
FELIDA. 
The discovery of extinct species from time to time, renders it 
necessary to re-examine the definitions of the families and genera 
into which living forms naturally fall. We thus learn the charac- 
ters of their primitive types, and the successive steps through which 
they passed in attaining their present characteristics. The Felidx 
are known as that family of Carnivora in which the feet and 
teeth are most specialized for the functions of seizing and lace- 
rating living prey. The number of living species enumerated by 
Dr. Gray is sixty-four, which he throws into a number of genera. 
The extinct species yet known are less numerous, but they present 
a greater variety of structure than the former. Two types or 
series may be recognized among the genera, namely those repre- 
sented by the genera Felis and Macherodus respectively. All of 
the latter are extinct. 
The greater number of the genera allied to Macherodus are 
distinguished by the great development of the superior canine 
teeth, whose crowns are generally compressed and trenchant. 
The corresponding part of the mandible is expanded downwards 
so as to furnish a protection to the slender crown from fracture ~ 
by lateral blows when not in use, but in some of the genera, e. g. 
Nimravus, this flange is not developed. The only definition 
which can be used to distinguish these sections of the family, is 
found in the angular separation of the anterior and lateral planes 
of the ramus of the mandible, and this character cannot be ex- 
pected to remain unaffected by future discovery. Forms will 
doubtless be found in which the angle is obsolete, and in which 
the lateral and anterior faces pass gradually into each other. 
Other characters which distinguish the extinct genera are found 
in the numbers of molar teeth, and, what has been heretofore 
neglected, the number of lobes of the molars themselves. 
As regards the existing genera, Dr. Gray' has brought out their 
1 Catalogue of Carnivorous, Pachydermatous, and Edentate Mammalia 
in the British Museum. By John Edward Gray, F.R.S., V.P.Z.5., F.L.S., 
etc. London, 1869. 
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