444 Thorpe — Some Tertiary Car niv or a in 



Measurements. 



Cat. No. 

 12803 



Y. P. M. Holotype 

 mm. mm. 



Molar-premolar series, length 58 55 



Premolar series, length 32 31 



P 2 , ant. -post, diameter 7 



P 3 , ant.-post. diameter 9.5 



P 4 , ant.-post. diameter 13* 



M 1} ant.-post. diameter 17.5* 14.5 



M 2 , ant.-post. diameter 9 



Depth of ramus at sectorial 25 • 25 



* Alveolar measurements. 



Potamotherium lycopotamicum (Cope). 



The type of this species, from the Mascall beds of 

 Oregon, has unfortunately been lost. It was based on a 

 jaw broken away immediately behind the carnassial, and 

 belonged to an animal about the size of a mink. The 

 type was figured in 1915 (Cope-Matthew). 



Two lower jaws, collected on the Niobrara River, are 

 referred to this species. One, from "Quarry D," Ft. 

 Niobrara Bird Reservation, Nebraska, Cat. No. 12834, 

 Y. P. M., found by Professor Lull in 1914, has the carnas- 

 sial unworn and intact, as well as the premolar alveolar 

 parapet, with the ramus below intact. It also possesses 

 the alveolus of M 2 , the presence or absence of which in 

 this species has not before been determined. All of the 

 premolars are two-rooted except the first. The other 



Measurements. 



Cat. No. Cat, No. 



12834 12825 



Y.P. M. Y.P.M. Holotype 



mm. mm. mm. 



Molar-premolar series, exclusive of M 2 . . 22 22 



M 1? ant.-post. diameter 7.1 6.6 



M 1? transverse diameter 3.8 4 



M 1; length of heel 2.4 2.4 



P 4 , ant.-post. diameter 4.2 4.5 



P 3 , ant.-post. diameter 3.8 



P 2 , ant.-post. diameter 3.4 



Depth of ramus below sectorial 7 



