NATURAL SCIENCES OP PHILADELPHIA. 169 



others. The back lobe, second in size, is thickest internally. The 

 fore and aft diameter of the last lower molar is equal to the cor- 

 responding upper tooth. 



The depth of the lower jaw at the last molar is three and a 

 quarter inches. 



The humerus is nearly a foot and three-fourths in length and 

 seven and a half inches in breadth at the condjdes. 



I propose to name the great pachyderm of the Uinta country, 



the UlNTATHERIUM ROBUSTUM. 



If not the most interesting, the most exciting incident of our 

 exploration of Diy Creek buttes was Dr. Corson's discovery of the 

 upper canine teeth, apparently of the most formidable of Carnivores, 

 the enemy of the Uintatherium, Paleeosyops, and other peaceful 

 pachyderms. The teeth resemble in their form those of the Sabre- 

 toothed Tiger. The more perfect specimen consists of nearly nine 

 inches of the enameled crown. In its perfect condition the tooth 

 measured upwards of a foot in length, so that it exceeded the 

 canines of the great Brazilian Machairodus. The tooth is sabre- 

 like, curved, and compressed conical. Its most remarkable cha- 

 racter consists in the lance-head-like form of the terminal three 

 inches. It is thickened at the axis, and impressed and expanded 

 towards the edges, so as to be actually broader in one portion 

 than immediately above. The antero- posterior diameter of the 

 crown near its base is two inches ; the thickness over an inch. 



These canine teeth terminating in lance-like points must have 

 proved most terrific instruments of slaughter. Their possessor 

 was no doubt the scourge of Uinta, and may therefore be appro- 

 priately named Uintamastix atrox. 



On favorable report of the committee, the following paper was 

 ordered to be printed : 



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