Wortman — Studies of Eocene Mammalia, etc. 433 



Art. XXXVI. — Studies of Eocene Mammalia in the Marsh 

 Collection, Peaoody Museum; by J. L. Wortman. (With 

 Plates VII and VIII.) 



[Continued from p. 206.] 



Family Hycenodontidce. 



Still another group of the Creodonta is the family Hyseno- 

 dontidse, which, like so many representatives of the Carnivora 

 already noticed, appears suddenly in the lower stages of the 

 Middle Eocene or Wasatch deposits, without any previous 

 announcement in the way of ancestors in the underlying Tor- 

 re jon. The present association of the genera in this family is 

 very different from that adopted by Cope, Scott, and Schlosser. 

 For example, Cope placed Hycenodon by itself in a separate 

 and distinct family ; Pterodon was arranged in the Oxysenidse ; 

 while Sinopa (Stypolophus), Proviverra, Quercytherium, and 

 Didelphodus were classified in the family Leptictidse. Both 

 Scott and Schlosser arranged Oxymna, Protopsalis, Hemip- 

 salodon, Pterodon, Dasyurodon, Thereutherium, and Hyceno- 

 don, in the family Hysenodontidse, at the same time placing 

 Patriofelis in the Palseonictidse. The genera Sinopa, Pro- 

 viverra, Quercytherium, and Didelphodus were placed by 

 them in a distinct family, Proviverridge. The first important 

 advance over this arrangement of the genera into family 

 groups was made in 1894,* when I pointed out that Oxyama 

 and Patriofelis are nearly related types, and should be classi- 

 fied in the same family ; that Protopsalis is probably the same 

 as Patriofelis y that neither of these genera is closely related 

 to Hycenodon ; but that Ilycenodon and Sinopa {Stijpolophus) 

 are closely related to each other. In the same year, Osborn 

 and myself added Pterodon to the two last-mentioned genera, 

 from a consideration of the teeth. f The close relationship of 

 Proviverra, Cynohyamodon, and Quercytherium, to Sinopa, 

 was then well known, and the inference was clear that these 

 forms follow Sinopa wherever placed in the classification. In 

 further elaboration of these views, I published in 1899 % a brief 

 classification of the three families Hy^enodontidse, Oxyeeniclse, 

 and Palseonictidse, which, I may add, forms the basis of our 

 present understanding of the arrangement of these three 

 important groups of the Carnivora. 



As regards the definition of the Hysenodontidse, if we leave 

 out of consideration Palwosinopa and Didelphodus, which more 

 probably are members of the Insectivora rather than of the Creo- 



*Bull. Amer. Mus. Nat. Hist., 1894, pp. 152, 156. flbid., 1894, p. 237. 

 tlbid., 1899, pp. 139, 140. 



Am. Jour. Scl— Fourth Series, Yol. XIII, No. 78.— June, 1902. 

 30 



