436 G. I. Adams — Extinct Felidoe of North America. 



With the higher genera they attained an enormous develop- 

 ment, such as would seem to have been a positive hindrance in 

 biting and seizing. In the true cats the canines remained 

 sub-equal although developing to a great size. 



The development of a flange on the anterior inferior portion 

 of the mandible is to be correlated with the lengthening of 

 the superior canines. Its function seems to have been to pro- 

 tect these teeth, but in the latter genera the length of the 

 flange evidently was not as great and the canines extending 

 below the mandible were effective weapons when the mouth 

 was closed. The most primitive forms probably possessed no 

 flange since the canines were short and sub-equal. In Archce- 

 lurus we see the first indication of a developing flange in the 

 obtuse angle of the mandible and the shallow fossa in which 

 the superior canine rests. 



The evolution of the Felidse is best indicated in the characters 

 of the dentition. It is upon the dental formulae and dental 

 structure that generic distinctions rest, and a careful study of 

 these points will reveal the genetic and phylogenetic relation- 

 ships of the family. 



The Succession of Genera. 



There are two distinct types of development among the 

 Felidae. Of these the Machserodont type seems to have had 

 its origin in America, since with the exception of JElurogale 

 and possibly Machmrodus all the genera have been found here. 

 The Old World was probably the home of the true cats, as it 

 seems to be to-day. The only representative of them in 

 America previous to Pliocene times was Pseudailurus, of 

 which genus only one specimen has thus far been found. This 

 genus may have been acquired through Oligocene intermigra- 

 tion, and the genera jElurogale and Machairodus are proba- 

 bly European descendants of American forms. 



Any attempt at a phylogenetic arrangement of the Felidse 

 must coincide with the occurrence in time, the order of 

 reduction of the dental series, and the development of the 

 individual teeth, particularly the sectorials. It is proposed 

 herein to show that there is a succession of genera of the two 

 types above mentioned which meets these requirements. 



Of the Machaerodont type the somewhat problematical form 

 from the Bridger described by Wortman as % Patriofelis 

 leidyanus is the most primitive. From it Dinictis* is deriv- 

 able, through the reduction of the size of the postero-internal 



* D. fortis has been described as having the second lower molar very rudi- 

 mental. In a specimen in the American Museum this tooth is absent from one 

 side. In D. paucidens described by Mr. Riggs in the Kansas University Quar- 

 terly, April, 1896, it is absent from both sides. The dental formula of D. fortis 



is thus M , D. paucidens probably being a synonym. 



