3 



Measurements. M. 



Length of molar series 180 



Diameter of canine tooth 033 



Length of premolars 093 



" " No. 3 035 



" molar No. 1 024 



" " No. 2 027 



Width " — 022 



Length " No. 3 041 



Width " " 024 



Depth ramus at molar No. 2 073 



This species betrays more of suilline character than any yet discovered 

 in the Bridger series, but that it has any such affinity has yet to be shown. 

 It was about as large as a fully-grown cow. 



Bathmodon. 

 Some of the species of this genus possess powerful cylindric tusks of 

 considerable length. The inferior tusks are sub-horizontal and promi- 

 nent. In metaloplwdon the superior tusks are compressed and knife-like. 



Phenacodus primaeous. Gen. et sp. nov. 



Char. Gen., as expressed by a posterior superior molar tooth. Crown 

 transverse, a little narrower and more strongly convex at the inner than 

 the outer extremity. It supports five rather low and obtuse tubercles, 

 two exterior and those on the inner side. Outer tubercles well inside the 

 outer margin of the crown, the one sub-triangular in section, the other 

 more nearly conical, the two connected by a low ridge which encloses a 

 concavity with the outer margin of the crown. There inner tubercles 

 arranged on the segment of a circle, sub-equal the lateral of one side, 

 connected with the exterior tubercle of the opposite side by a low ridge, 

 which encloses a basin with the inner tubercles. 



Char. Specif. Median of the three inner tubercles stouter than the 

 others. No noticeable basal cingulum. Two compressed roots with 

 axes at right angles to each other, and very large pulp cavities, and thin 

 walls. 



Measurements M. 



Width of crown 0.0140 



Length " 0093 



Elevation of outer cones above shoulder 0050 



Width between apices of outer cones 0060 



median " 0050 



This tooth more nearly resembles the type of those of the lower 

 quadrumana of the Bridger Eocene, but also more remotely of the suil- 

 line genus Elotherium. It would represent an animal as large as the 

 orang. The only one of the genera named by Marsh, to which I can 

 trace any likeness is his Thinotherium, described from inferior molars. 



