1880. 



81 



[Cope. 



the full number of true molars is retained in some genera, as AmpMcyon, 

 and only one lost in Gdnis. Secondly, the tubercular character of the 

 posterior molars in both jaws in the Canidm is distinguished from their 

 sectorial character in FelidcB. Estimated by these tests the Miaddce. are 

 clearly the forerunners of the GaMdm, and the Oxymnidce of the Felidw. 

 In Miacis we have in fact a near approach to the dentition of Oanis, in the 

 lower jaw ; while in the same part of BidymitUs posterior abbreviation 

 has commenced, reminding one of Ywerra. In the Oxymnidce, one degree 

 of posterior abbreviation is seen in Siypolophus, where the last superior 

 molar is narrowed and turned at right angles lo the others. In Oxywna, 

 the process had advanced a step, for there are but two superior true molars, 

 and the last of these is driven in, transversely. The first true molar is func- 

 tionally sectorial in this genus, while the last premolar is the true sectorial of 

 tlie superior series in existing Carnwora. In the inferior series there are 

 only two true molars in Oxymna, both primitive, or " tubercular-sectorial " 

 in character. In existing FelidoB the second is lost, while the first undergoes 

 great changes in becoming a specialized sectorial. The forms of the Felidm, 

 which are nearest, are the Gryptoprocta, and the Procelurus of Filhol, but 

 they only follow after a wide interval. I have elsewhere discussed the 

 successive steps in the evolution of the sectorial itself* I have also 

 pointed outf the successive shortening of the anterior part of the dental 

 series in the Felidm and other groups of existing Garnivora, which came 

 later in time. 



The following table will give an idea of these afiinities, and the phylog- 

 eny to be derived from them ; 



Felidse. Canidae. 



Felidse. 



Canidae. 



Hysenodontidae. 



OxycBua. 



\ 

 Stypolophus. 



\ 

 Oxysenidse. 



Miacidae. 



Mesonychiida3. 



Amblyctonidse. 



Synonymy. Prof. Gaudry has united Stypolophus {Gynohycenodon 

 Filhol) with Proviverra. After an examination of casts of Riitimeyer's 

 types preserved in the Museum of the Jardin des Plantes, I retain them as 

 distinct for the reasons given above. Mr. Bose in an interesting paper on 

 tills subject published in the London Geological Magazine for May and 



* Proceedings Acad. PUila., 1875, p. 21. 

 t Felidse and Canidse, 1. c, 1879, p. 169-170. 



PROC, AMER. PHILOS. SOC. XIX. 107. K. PRINTED SEPTEMBER 9, 1880. 



