UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 6, No. 17, pp. 401-402 Issued November 1, 1911 



A FOSSIL BEAVER FROM THE KETTLEMAN 

 HILLS, CALIFORNIA 



BY 



LOUISE KELLOGG 



The finding of a fossil beaver tooth in a formation much 

 earlier than any in which this animal has hitherto been found 

 in this country is the work of Mr. W. H. Ochsner, of Palo Alto, 

 California. He discovered the tooth at the north end of the 

 Kettleman Hills, Fresno County, California, in a formation 

 which he considers Middle Etchegoin, corresponding- approxi- 

 mately to the late Miocene or early Pliocene, and kindly sent the 

 specimen to the palaeontological collection of the University of 

 California. Up to this time the earliest known occurrence of 

 the true beaver, Castor, in America, was in the Pleistocene of 

 the Silver Lake region, Oregon, so that the finding of this genus 

 in beds as early as the late Miocene or early Pliocene is an 

 interesting and important discovery. 



Although only the one tooth, M 2 , no. 1940S, is available, it 

 possesses one character, namely, that the anteroposterior diam- 

 eter is greater than the transverse, which is considered sufficient 

 ground to make it, at least tentatively, a new species, Castor 

 calif ornicus, and it may be presumed that, if more material were 

 available from the same source, this would exhibit additional 

 characters to further establish the new species. The tooth is 

 remarkably close in pattern to those of the various species of 

 Castor found on the Pacific Coast, but in all of the Recent skulls 

 examined the transverse diameters of the molars is either the 

 same as the anteroposterior diameter or greater than this diam- 



