Genera o/" Felicia?, and Canidse. 43 



In the existing Cryptoprocta ) which Gervais has shown to 

 be nearly allied in dentition to Psezidcelurus, the lobes are 

 wanting from both jaws ; but this genus adds to this primi- 

 tive character another of modern significance, viz. the presence 

 of the anterior cusp of the superior sectorial. Moreover 

 Cryptoprocta has another peculiarity, which recalls the genera 

 of the Eocene Creodonta, in the well-developed interior 

 tubercle of the third premolar, a character unknown in Mio- 

 cene or existing Carnivora. That genus is evidently, like 

 the Lemuridse (also of Madagascar), a remnant of the Eocene 

 fauna, which once covered most of the earth, and may 

 be regarded as, on the whole, the most primitive of the 

 Felidaj, recent and extinct. 



Following the two lines of Felidas already indicated we 

 attain the same conclusion in both, by the same stages. 

 The primitive form of the Machserodont line, represented by 

 Hoplophoneus, has its extreme in Eusmilus, where the second 

 inferior premolar and an incisor tooth are wanting, giving a 

 formula of I. 2, C. 1, Pm. 1, M. 1. In Machcerodus we 

 have the modern characters of the molars seen in Felis, viz. 

 no heel of the inferior sectorial, the superior sectorial with 

 an anterior lobe, and posterior lobes of the premolars. The 

 extreme of this line is reached in Smilodon, where the second 

 inferior premolar is one-rooted or wanting. This genus, then, 

 stands related to Machcerodus as Eusmilus to Hoplophoneus. 

 In the Feline line proper, on reaching the existing genera, we 

 have lost the heel of the inferior sectorial and gained the 

 posterior lobes of the premolars and anterior lobe of the supe- 

 rior sectorial at once. A further modification of the dentition 

 of the superior series of the recent forms is seen in the loss 

 of the first superior premolar in Lyncus and Neqfelis. Still 

 another, which is one step beyond what is known in the 

 Machrerodont line, is the loss of the interior tubercle of the 

 superior sectorial, which characterizes the genus Cyncelurus. 

 A superior sectorial tooth having the character of that of this 

 genus was discovered by Dr. Hayden in the Loup-River 

 formation of Nebraska, and was referred to a species by Dr. 

 Leidy under the name of JElurodon ferox. It was much 

 larger than the C.jubatus. 



As already remarked, the genera of the Machasrodont line 

 are extinct, and this in spite of the fact that they presented 

 the most perfect weapons of destruction in their canine teeth 

 from the earliest times. Their other modifications of struc- 

 ture advanced par 'i passu with those of the Feline series ; and, 

 among others, the feet presented, in the later forms at least 

 (e. g. Smilodon riecator, Gerv.), the most perfect prehensile 



