NO. 2 A STUDY OF MENISCOTHERIUM GAZIN 89 



and Clarkforkian Paleocene. The fourth premolars above and 

 below show no approach toward the molariform condition observed 

 in M eniscotherium. The outer wall of the upper molars shows some 

 tendency toward the stylar condition in the latter, but the accessory 

 cuspules are situated on the crests or horns of the protocone. In 

 M eniscotherium these cuspules are distinctly separated from the 

 protocone, with the protoconule independently crescentic and the 

 metaconule aligned in a crest with the hypocone. Moreover, the 

 distinct cingulum around the protocone of M eniscotherium is missing 

 in Protoselene. The lower molars would seem to possess an equiva- 

 lent potentiality, but the trigonid is comparatively short and the 

 paraconid arm or crest has become rather abbreviated in the earlier 

 form. Possibly Protoselene is better situated in time and in the 

 character of the accessory cuspules of the upper molars for a possibly 

 closer affinity to the litopterns than are any of the other North Ameri- 

 can Paleocene condylarths. 



