

140 Wortman — Studies of Eocene Mammalia. 



developed in the first molar, and has nearly the same relations 

 as in the corresponding tooth of Omomys Carteri. In the 

 second molar, however, this cusp has a much more posterior 

 position and is decidedly smaller, while in the third it is com- 

 pletely absent. The last molar is narrower and more reduced 

 than in Omomys, and the heel lacks the distinct pointed cusps 

 seen in all the species of that genus. The crowns of the upper 

 molars, especially that of the second, are almost as wide in 

 front as behind, being in marked contrast with the molar 



133 



134 



Figwre 133. — Two superior molars of Euryacodon lepidus Marsh ; crown 

 view ; a little less than four times natural size. (Type of genus and species.) 



Figure 134.— Lower jaw fragment of Euryacodon lepidus Marsh ; side 

 and crown views ; two and one-half times natural size. 



crowns of the species of Omomys. Thus it will be seen that 

 the lower molars of Euryacodon are more advanced than those 

 of Omomys, and there can be apparently very little doubt 

 that they represent distinct genera. 



The complete dentition of the lower jaw is unknown, and I 

 have provisionally referred the genus to the Omomyinse. A 

 comparison with the type of Cope's Anaptomorphus cemulus, 

 from the lower horizon of the Bridger beds, shows many 

 points of similarity. As is well known, the type of this latter 

 species consists of a lower jaw in which the first and second 

 molars are present, but the third is missing from the specimen. 

 In Anaptomorphus the anterior cusp of the trigon has disap- 

 peared in both the first and second molars, which at once 

 establishes the fact that it is at least a different species from 

 Euryacodon lepidus and the most advanced form of Primate 

 thus far known from the American Eocene. It is upon this 

 account that I have chosen to regard Euryacodon and Anapto- 

 morphus as distinct from each other, until the full dentition of 

 the former and the upper teeth of the latter are more fully 

 known. If Euryacodon is eventually found to possess only 

 two premolars in the lower jaw, it will then probably be 

 necessary to unite the two genera under the name Euryacodon, 

 since the latter has distinct priority over Anaptomorphus. 



[To be continued.] 



