402 



University of California Publications. 



[Geology 



eter, while the fossil form shows a distinct increase in the antero- 

 posterior diameter over the transverse. Comparison with M 3 of 

 Castor neglectus Schlosser, from the Bohnerzen of Melchingen, 

 Germany, exhibits some similarity of pattern, and that tooth 

 also is one in which the anteroposterior diameter exceeds the 

 transverse, but it is M 3 , and shows a narrowing posteriorly, which 

 makes it decidedly .different in shape from Castor calif or nicAis, 



lb lc 



Figs, la to lc. Castor calif or nicus, n. sp., Etchegoin formation, Kettle- 

 man Hills, California; all figures twice natural size. Fig. la, occlusal view; 

 fig. lb, inner side ; fig. It', posterior side. 



although there is but a slight difference in the diameters. 

 Dipoides problematicus Schlosser, from the same locality as 

 Castor neglectus, is allied to these two Castor forms in pattern, 

 but it is much smaller. Prom Eucastor Leidy, Castor calif ornicus 

 differs distinctly in having three enamel folds in its outer wall 

 instead of the one characteristic of that genus and of Tro- 

 gontherium. 



Measurements, M 2 , no. 19408 



Anteroposterior diameter 6.8 mm. 



Transverse diameter 5.8 



Transmitted May 16, 1911. 



