70 



but the external is spinous in character, while the internal is 

 stout and obtuse. The anterior slope of each lobe is steep, 

 while the posterior is long and gentle. As in U. robustuju, 

 there is a small rounded tubercle on the inner side of the pos- 

 terior basal ridge ; but there is no tubercle occupying the 

 entrance of the triangular valley between the lobes. The 

 enamel of all the molars is smooth. 



Tcctli Mcasitrcments. 



M. 



Length of molar series • 148 



Length of premolar series -062 



Length of true molar series -089 



Fore-and-aft diameter of second premolar -022 



Transverse diameter of second premolar -023 



Fore-and-aft diameter of third premolar -022 



Transverse diameter of third premolar -023 



Fore-and-aft diameter of first molar -023 



Transverse diameter of first molar -026 



Fore-and-aft diameter of second molar -028 



Transverse diameter of second molar -031 



Fore-and-aft diameter of third molar -039 



Transverse diameter of third molar -044 



Distance between last molars 058 



Distance between first premolars -049 



Distance between first molars -074 



Fore-and-aft diameter of root of canine -060 



Transverse diameter of root of canine . 039 



Length of diastema -072 



Distance between canine alveoli -080 



Lozver Jan'. — Dr. Leidy has very kindly sent us some of 

 the lower molars of an undescribed Uintatheriuvi, which may 

 belong to this species. They consist of the anterior lobe of 

 the last molar, and second and third premolars entire. They 

 all have nearly the same conformation, consisting of three 

 acute pyramidal lobes, of which the anterior is very much 

 the highest and broadest ; the median lobe is partly separated 

 from the anterior by a valley which opens outwards, while 

 the valley between the posterior and median lobes passes 

 completely across the tooth. The highest point of the crown 

 is the inner end of the anterior lobe ; but the difference be- 

 tween this and the outer end, very great in the molars, be- 

 comes slight in the premolars. The inner end has an acces. 



