NEW AND CHARACTERISTIC SPECIES OF FOSSIL MOL 

 LUSKS FROM THE OIL-BEARING TERTIARY FORMA- 

 TIONS OF SOUTHERN CALIFORNIA. 



By Ralph Arnold, 



Paleontologist, U. S. Geological Survey. 



INTRODUCTION. 



Among the fossils commonly found in or characteristic of certain of 

 the oil-bearing Tertiary formations of southern California are the 

 species and varieties mentioned in the following pages. The new 

 forms are described and figured; those previousl}" described are simply 

 figured, but a brief note concerning their occurrence is inserted in the 

 explanation accompanying each drawing. It has been deemed advis- 

 able to insert figures of the old species in this paper because the descrip- 

 tions and illustrations of these forms are in publications inaccessible to 

 most readers, and it is essential for the proper identification of the 

 faunas that certain of the old species be known. The difi^erentiation 

 of the various geologic formations in the southern coast ranges of Cali- 

 fornia depends almost entirely upon their palentology, so that it has 

 been the aim of the writer to give in this paper those species and only 

 those which will aid in the determination of the horizon of the various 

 faunas found in that region. These fossils, together with some others, 

 will be figured on Plates XXV to XLI, Bulletin No. 309, U. S. Geo- 

 logical Survey. 



The following new species and varieties are found in the yellow 

 sandstone of the lower Miocene at the head of Topauga Canyon, 3 

 miles south of Calabasas, Los Angeles County, California. 



LIST OF LOWER MIOCENE FOSSILS FROM TOPANGA CANYON. 



Myiilus mathevsonii Gabb var. e.vpaiisn><, new variety. 



Cerithium topangensis, new species. 



Chlorostoma dalli, new species. 



Bathytoma keepi, new species. 



Macron merriami, new species. 



Ocinebra toimngensis, new species. 



Purpura edmondi, new species. 



Sigaretus perrini, new species. 



Turbo topangensis, new species. 



Proceedings U. S. National Museum, Vol. XXXII— No. 1545. 



525 



