ipoi.] Matthew, Additional Observations on the Creodonta. 5 



Thus, as far as it goes, this distinction coincides with that 

 between the Creodonta adaptiva (carnassial ^) and Creodonta in- 

 adaptiva (carnassial not — ). Arctocyon must be included with 

 the adaptive types and Mesonyx with the inadaptive, although 

 they have no true carnassials, an arrangement which seems to be 

 supported by a variety of minor skeletal characters. But the 

 evidence is entirely inadequate at present to use this as a primary 

 basis of division. Its constancy in both the small and large 

 genera of a family has not been proved, and until this is proved 

 it is always possible that the blunt claws are correlated with the 

 size of the species, not with its true relationships. 



Zittel ('94), following Schlosser and Scott in large part, di- 

 vides the Creodonta as follows (I omit invalid or unimportant 

 genera) : 



I. OxyclcBiiida:. Molars tritubercular, pointed cusp, no shear ; premolars 



trenchant. Oxyclamis, Chriaciis, Protochriacus, Tricentes, Rlioclcenus, 

 Protogoiwdon. 



II. Arctocyonidcc. Molars quadritubercular, low-cusped, no shear ; premolars 



trenchant. Arctocyon, Clcenodon, Anacodon. 



III. Triisodontida. Upper molars tritubercular, lower molars with two high 

 cusps and talonid. No shear. Premolars high and pointed. Triisodon, 

 Goniacodon, Microclcrnodon, Sarcot/trausteu. 



IV. Alesonychidcs. Upper molars tritubercular, lower molars with high and low 



cusp and talonid. No shear. Premolars high and pointed. Dissacus, 

 Pachycena, Mesonyx. 



V. ProviverridcE. Upper molars and p^ tritubercular, protocone far in and 



well forward. Lower molars with high tricuspid trigonid and low 

 talonid. Hycenodictis, Deltatheritim, Siiiopa, Proviverra, Quercythe- 

 riiiiii, Didelphodzis, Prorhyzccna. 



VI. PalcconictidcB. Jaw shortened. Third upper and lower molar absent. 



Molars tritubercular, p^ and niy large. Premolars thick. Palceoiiictis, 

 Amblyc tonus, Patriofelis. 



VII. Hycenodontidcr. Upper molars with external blade and internal tuber- 

 cle. Third upper molar transverse or absent. Lower molars sectional 

 with low, trenchant heel. Oxya-na, Protopsalis, Heiiiipsalodon, Pterodon, 

 Dasyurodon, Thereutheritim, Hyccnodon. 



VIII. Miacidce. p^ and mj carnassial. Last upper molar small, transverse. 

 Aliacis (= Uintacyon), Didymictis (= Viverravus), ? Vtdpavus. 



The following changes, mainly dependent on recent discoveries, 

 seem advisable : 



