298 PROCEEDINGS OF THE ACADEMY OF [1892. 



ELLIPSODON. gen. nov. 

 Syii. Tri'ceiites Cope, in part. 



The systematic position of this form is entirely obscure; it agrees 

 with Tr'icentes in having but three upper premolars, but differs 

 entirely in the construction of the molars. The premolars are 

 relatively broad and massive, almost as in MlodcBnus ; P4 is esj^e- 

 cially broad and has a very large deuterocoue. The molars are 

 oval in shape and have no hypocone ; '^ is the largest of the series 

 and '^ very greatly reduced and forms a mere oval-shaped rudi- 

 ment, without recognizable elements. Inferior dentition unknown. 



One species : E. (Triceiites) iiuequidens Cope. Puerco. 



Though technically Chriacvs and its allies, so far as their struct- 

 ure is at pi'esent known, belong among the creodonts, their general 

 aspect is very similar to that of the Eocene Primates and it is diffi- 

 cult to resist the suspicion that they will eventually prove to be 

 primitive ancestral forms of that group. 



ARCTOOYONID^ Cope. 



Superior molars more or less completely quadritubercular ; tri- 

 gonid of lower molars very little or not at all higher than talon ; 

 paraconid much reduced or absent; all cusps of molars low and 

 massive, premolars high and acute. 



CLJENODON, gen. nov. 

 Syn. Mioclicnus Cope, in part. 



In the present state of knowledge it is very difficult to justify the 

 separation of this form from the European genus ^rctoc?/on and yet 

 the identification of genera from different continents upon insuffi- 

 cient materials is quite as apt to lead to erroneous conclusions in 

 questions of geological correlation and zoological distribution, as 

 the opposite course is to cause confusion from a systematic point of 

 view. In view of this choice of evils, I have provisionally sug- 

 gested a new name. A not unimportant difference from Arctocyon 

 is the less completely quadritubercular character of the upper 

 molars. From Hyodectes it differs in the greater simplicity of the 

 molars and lack of secondary tubercles, as well as in the less 

 extreme reduction of m^, while it may be distinguished from Hetero- 

 borus by the presence of p^, which is absent in that genus. In Cl(je- 

 nodon the upper molars are subquadrate in outline, with fairly well 

 developed hypocone. M2^is the largest of the series, 1^ the smallest. 



