F. B. Zoomis — Wasatch and Wind River Rodents. 127 



two anterior cusps very close, the internal one being much 

 higher than the external cusp. The wide molars have the two 

 posterior cusps united by the posterior marginal ridge. The two 

 anterior cusps on the other hand are not yoked, though an 

 anterior marginal ridge starts from either one but dies down 

 about midway. The mesostylid is very small. An incisor is 

 of medium thickness, measuring on a broken surface 5-J mm 

 deep by 2-J mm wide. The length of the four lower molariform 

 teeth is 18 mm . 



Paramys atwateri sp. nov. 



Type No. 180, a lower jaw of the left side containing molars 

 1 and 2 and the roots of the other teeth, and found at the foot 



Fig. 3. Paramys atwateri, x 4 ; lower jaw of the left side. 



of Tatman Mt. near Otto, "Wyo. The species is named after 

 Mr. W. C. Atwater, a patron of the expedition. 



This is the smallest of the Wasatch species, and character- 

 ized by the very plump cusps which are placed further in 



Fig. 4. Paramys bicuspis, x 4 ; A', molars of the right lower jaw ; B, 

 premolar 4 and molars 1 and 2 of the left upper jaw. 



from the margin than in other species, in consequence of 

 which the interior basin is much reduced in extent. The two 

 anterior cus]3s are united by a marginal ridge, as are also the 

 two posterior cusps. The mesostylid is relatively large. The 

 face of a broken incisor measures 3|- mm deep by 2 mm wide. The 

 length of the series of lower molariform teeth is 12-| min . 



