Wortman — Studies of Eocene Mammalia, etc. 115 



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

 Collection, Peabody Museum ; by J. L. Wortman. 



[Continued from page 46.] 



Family Oxycenidce Cope. 



With the Oxysenidse we enter upon the consideration of a 

 group of the Creodonta in which the teeth had already made 

 considerable progress towards the more typical sectorial struc- 

 ture, even at the beginning of the Wasatch, in which deposits 

 their remains are first met with. This family is represented 

 in this horizon, as far as now known, by the single genus 

 Oxycena Cope, containing two, or perhaps three, w T ell-marked 

 species of fairly sizable dimensions. No species that can be 

 placed ancestral to it have as yet been found in either of the 

 older Torrejon or Puerco Beds, and it would appear probable 

 that they were migrants from the north or from Asia, along 

 with the Artioclactyle and Perissodactyle Ungulates, the 

 Primates, certain of the Carnassidents, including the Felids 

 and Canids, the Rodents and others, at the beginning of the 

 Wasatch epoch. These two or three species appeared simul- 

 taneously at all the localities of the Wasatch, in the Big Horn, 

 Bear River, and San Juan Basins, and this fact of itself would 

 seem to indicate a very general and widespread distribution. 



The probable immediate successor of the genus in the Wind 

 River deposits is a species which Cope referred to the distinct 

 genus Protopsalis ; but I have pointed out* that this genus, 

 as far as at present known from fragmentary Remains, does not 

 differ material^ from one of the Briclger representatives which 

 Leidy described under the generic title of Patriofelis. It 

 should be borne in mind, however, that this Wind River form 

 is known from a few fragments only, and it will be somewhat 

 surprising if, when its osteology is more completely known, it 

 does not exhibit a stage of development intermediate between 

 Oxycena and Patriofelis. In the Bridger, the main Oxycena 

 line is continued in the two species of Patriofelis, large, 

 powerful Creodonts in which the teeth had become much 

 specialized and reduced in number, in a manner not dissimilar to 

 that of the Felids. In this stage also appears suddenly, without 

 any known forerunners in any older formation, a less distinctly 

 specialized type, Limnocyon Marsh, in which the teeth are 

 more generalized than in Oxycena. The genus is represented 

 by three or four well-marked specific modifications, one of 

 which persisted to the close of the Eocene, in what I have 



* Bull. Amer. Mus. Nat. Hist., 1894, p. 130. 



