1916] Merriam-Stock-Moody : An American Pliocene Bear 91 



The large, heavy-fanged canines (figs. 1 and 2) are of the char- 

 acteristic ursid type. The crowns of the upper canines have 

 dimensions and proportions near those of A. si inn in of Potter Creek 

 Cave. The roots may be larger relative to the size of the crown 

 in the Rattlesnake specimen, but are not thicker in either transverse 

 or anteroposterior diameter. In the lower canines, as in A. sun ion, 

 the crowns are sharply concave on the posterior side. As in the 

 upper canines, the crowns are near the size of those in A. si nut in, but 

 the roots seem relatively large. 



Pi shows a form closely approaching that in the corresponding 

 tooth of A. si nut m. This tooth (fig. 3) has a simple single root; and 

 the crown consists of a single cusp, which extends 

 to the anterior and posterior borders of the tooth 

 in a, well-marked longitudinal ridge or crest. Tin 1 

 anterior ridge is noticeably convex on the outer 

 side, and drops off abruptly or may be concave on 

 the median side. A distinctly marked ridge of the 

 cingnlum on the antero-internal side unites an- 

 teriorly with the principal crest. 



Fortunately both the right and left upper car- 

 nassials (P-) are represented. These teeth (figs. 

 4r? to 4c) are large and unusually well developed 

 for members of the Ursidae. They differ markedly 

 from all specimens of Ursus and Arctotherium 

 known to the writers, and approach closely the type of P- known in 

 the several species of Ryaenarctos (figs. 5 to 7) . In the Oregon species 

 the protocone is slightly larger than the tritocone. The deuterocone 

 is very large, approximating in its cross-section the size of the proto- 

 cone; and is situated so far forward that its anterior border is not 

 posterior to the corresponding border of the protocone as in Visits 

 and Arctotherium. A large protostyle is present. The tooth is 

 distinctly three-rooted, a large and widely divergent root supporting 

 the deuterocone. The outer contour of the tooth shows a distinct 

 concavity of the cingulum opposite the posterior side of the protocone. 



Pi differs from the corresponding tooth of Arctotherium in the 

 relatively large size of the deuterocone ; in the support of the deutero- 

 cone upon a distinct, widely diverging inner or third root; in the 

 situation of the deuterocone as far forward as the protocone ; and 

 in the presence of a large, distinctly separated protostyle. In all of 

 the characters in which this tooth differs from Arctotherium it re- 



Fig, 3. Indaro- 

 tos(?) oregonensis, 

 n.sp. Pi, no. 22362, 

 inner and occlusal 

 views, natural 

 size. Kattlesnake 

 formation, J o h n 

 Day Valley, Ore- 

 gon. 



