Genera o/" Felicia} and Canidge. 37 



the characters of their primitive types, and the successive steps 

 through which they passed in attaining their present charac- 

 teristics. The Felid«3 are known as that family of Carnivora 

 in which the feet and teeth are most specialized for the func- 

 tions of seizing and lacerating 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 represented by 

 the genera Felis and Machcevodus respectively. All of the 

 latter are extinct. 



The greater number of the genera allied to Machwrodus 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 down- 

 wards 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 expected 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 is obsolete and in which the lateral and anterior faces pass 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 number 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 characters more fully than any other author. He 

 points out the fact that in some of the species the orbits are 

 closed behind, and in others open. He first examined into 

 the manner of the contraction and closing of the pupil in the 

 presence of light, and pointed out the fact that in the large 

 cats it is always round and approximates to a point in closing, 

 while in the smaller forms the pupil closes as a vertical slit. 

 He shows that the cats of the former group have the smaller 

 orbits of the cranium, and the latter the larger. Dr. Gray, 

 however, uses other characteristics in the discrimination of the 

 genera, which are, in my estimation, quite inadmissible — as 

 the relative length of the muzzle and of the premaxillary 

 bones, also of the hair on different parts of the body and tail. 



* Catalogue of Carnivorous, Pachydermatous, and Edentate Mammalia 

 in the British Museum. By John Edward Gray, F.H.S., V.P.Z.tS., 

 F.L.S., &c. London, 1809. 



