UNIVERSITY OF CALIFORNIA 



Bulletin of the Department of Geology 



Vol. 1, No. 13, pp. 363-370. ANDREW C. LAWSON, Editor 



SIGMOGOMPftlUS LE CONTEI. 



A 



NEW CASTOROID RODENT 



FROM THE 



PLIOCENE NEAR BERKELEY, CALIFORNIA. 



I BY 



John C Merri-am. 

 CONTENTS. 



Occurrence 363 



History of the Castorida- 364 



Description 365 



Comparison with other Castoroid Genera 367 



Geological and Geographical Distribution of Castorida; 369 



OCCURRENCE. 



The fossil rodent remains here described and referred to the 

 Castoridae or beaver family, were found by the writer, about two 

 years ago, near Bald Peak, two miles east of Berkeley. The fresh- 

 water beds in which they were found form part of a very thick series 

 of gravels, clays, limestones, and eruptives belonging, according to 

 Prof A. C. Lawson, to the lower division of the Pliocene.* 



At the point where the rodent bones were found, the clays con- 

 tain abundant but fragmentary organic remains, including shells of 

 Limncea contracosta, Cooper; Planorbis pab/oanus, Cooper; Ano- 

 donta Nuttaliana, Lea var. lignitica, Cooper; Cypris, nov. sp.; Ancy- 

 Itis sp.; and Helix sp. Teeth of Lepus{~?) and the dentary bone and 



*The geology of the region in which these beds occur has been subjected 

 to detailed study by Prof. A. C. Lawson, with the collaboration in part of Dr. 

 Chas. Palache, and a monograph on the Pliocene rocks by these geologists is 

 shortly to appear. 



