Cope.] l^O [Dec. 16| 



II. One or more superior molars, with the external heel produced into 

 a blade. 



a, Molars 4 — 3 ; three last inferior tubercular sectorial. 



Premolars robust, conic Quercit7ierium Filh. 



Premolars compressed ; the fourth superior with a conic cusp and heel 



externally Stypolophus Cope. 



Premolars compressed ; fourth superior with a simple blade externally . . . 



Proviverra Rutim. 



OXY^ENID^E. 



I. Inferior molars without internal tubercles. 



Molars, f f ; three sectorials in the lower jaw Pterodon Blv. 



II. Inferior molars with internal cusps. 



a. Posterior heel of one or more superior molars elongate and trench- 

 ant. 

 Last inferior molar truly sectorial, without internal tubercle ; second, 



tubercular-sectorial Protopsalis Cope. 



Molars, £ § ; two last inferior molars tubercular-sectorial. . . Oxyama Cope. 



Amblyctonid^e. 

 Fourth inferior premolar with a broad heel supporting tubercles ; an 



anterior and no internal tubercles Amblyctonus Cope. 



Inferior molars with tubercular beel, an anterior and an internal tubercle. 



Periptychus Cope. 

 Dental formula below, 3, 1, 3, 3. Fourth inferior premolar with a cutting 



edge on the heel ; both internal and anterior tubercles 



Palceonyctis Blv. 

 Mesonychid^e. 



a. Inferior molars seven ; 



Cones of inferior and superior molars simple Mesonyx. 



Cones of last two inferior molars with lateral cusps.. Dissacus. 



aa. Inferior molars ? six. 



Internal lobes of penultimate superior molar v-shaped Sarcothraustes. 



aa. Inferior molars five. 



Inferior molars with strong anterior lobe. Patriofelis* 



Miacis canavus Cope. 



Bulletin IT. S. Geol. Survey, Terrs., 1881, p. 189. One mandible. 



Miacis brevirostris Cope, loc. cit. p. 190. 



Parts of four mandibles. 



DlDYMICTIS DAWKINSIANUS Cope, 1. C, p. 191. 



Six mandibular rami more or less complete. 



Individuals of the genus Didymictis are abundant in the Wasatch beds 



* Of uncertain reference to this family. 





