28 



E. M. MUSEUM MEMOIRS. 



extending the whole breadth of the crown. This tooth is much larger and less 

 worn than the preceding, with a strong, slightly serrated posterior basal ridge, 

 which recalls the corresponding ridge in the last lower molar. The crescentic 

 anterior ridge rises into high points at the extremities, giving a tripodal charac- 

 ter to the crown ; it projects beyond the line of the straight posterior ridge. 

 The accessory tubercle is large and shows a tendency to become double. In this 

 respect the tooth agrees with that of U. robustum, but there is no tubercle occu- 

 pying the entrance of the triangular valley between the lobes. 



As a whole the series diverge rapidly, but the distance between the first 

 premolars and posterior molars is about the same, owing to the great breadth of 

 the latter. The molars are distinguished from the premolars by the accessory 

 tubercle. The entire series present the outward opening V, the posterior ridge 

 in all being straight, the anterior curved forwards. 



Measurements and Relations of Upper Teeth. 



Lox. Uinta. 



M, M. 



Distance between canine alveoli, inner margins n .08 



Length canine-molar diastema 09 .072 



Fang of canine transverse diameter 04 .039 



Fore-and-aft diameter of ditto 065 .060 



Distance from canine to tips of premaxillaries 070 .09 



Length of molar series 169 .148 



Length of premolar series 074 .062 



Fore-and-aft diameter of first premolar 025 



Transverse diameter of first premolar 019 ... 



Fore-and-aft diameter of second premolar .022 



Transverse diameter of second premolar .023 



Fore-and-aft diameter of third premolar 025 .022 



Transverse diameter of third premolar 029 .023 



Fore-and-aft diameter of first molar 029 .023 



Transverse diameter of first molar 030 .023 



Fore-and-aft diameter of second molar 030 .028 



Transverse diameter of second molar 037 .031 



Fore-and-aft diameter of third molar 040 .039 



Transverse diameter of third molar 039 .044 



Height, crown of penultimate molar 021 .019 



Distance between molar series in front 072 .058 



Distance between molar series behind 06S .049 



Lower Jaw of Loxolophodon. 



The museum has not succeeded in obtaining a complete lower jaw of Uinta- 

 therium, though a portion of the jaw has been placed in position and figured 

 in Plate II. Marsh, however, at an early day described a jaw belonging to this 

 genus, with its remarkable lower flange opposite the upper canines, and with four 



