EXPLANATION OF PLATE 23. 



All figures are reproduced natural size. 



Figs. 1,2. Nothrotherium (?) shastense, n. sp. Eight ramus of the mandi- 

 ble viewed from above and from the inner side. 



Figs. 3,3a. N. ( ?) shastense. A superior molar of the same crown and 

 lateral views, showing the curvature of the tooth and the 

 pattern of the triturating surface. 



Figs. 4, 4</. N. (?) shastense. Left third inferior molar, showing the 

 pattern of the triturating surface and the concave anterior 

 wall of the tooth. 



Figs. 5, 5u. N. ( ?) shastense. Superior molar No. 8337, referred to the 

 same species as the above, showing the triturating surface 

 and the convex rib on the side of the tooth crown. 



Fig. 6. Megalonyx (?). View of the triturating surface of a molar (No. 

 8705, doubtfully referred to this genus. 



Fig. 7. Megalonyx wheatleyi (?). Crown view of amolar. The triturat- 

 ing surface is slightly broken. 



Fig. 8. Nothrotherium shastense. Triturating surface of the fifth 

 superior molar of the left side. The tooth has been damaged 

 by rodent gnawing and its outline is restored by a broken 

 line. The restoration is based on the shape of the tooth 

 shown at the margin of the pulp canal. 



