414 



University of California Publications in Geology 



[Vol. 13 



Panope californica, n. sp 427 



Gastrochaena, sp 428 



Odostomia santana, n. sp 428 



Epitonium, sp 428 



Amauropsis pseudoalveata, n. sp 429 



Gyrodes californica, n. sp 429 



( 'ei-it hium (?) suciaensis, n. sp 430 



Cerithium (?), sp 430 



Alaria nodosa, n. sp 430 



Aporrhais vetus, n. sp 431 



Siphonalia dubius, n. sp 431 



Lysis californiensis, n. sp 431 



Volutoderma magna, n. sp 432 



Volutoderma santana, n. sp 432 



Bullaria tumida, n sp 433 



Explanation of plates : 434 



INTRODUCTION 



The rich invertebrate fauna collected by the writer in the Santa 

 Ana Mountains of Southern California contains a number of mol- 

 luscan species that appear to be new to science. These 34 species are 

 herein described together with a few notations on other forms from 

 the same region. 



The general geologic and palaeontologic features of this region 

 have already been presented by Dickerson, 1 and in 1916 a detailed 

 discussion of the Cretaceous strata and contained fauna was published 

 by the writer. 2 



Three faunal zones were recognized within the Chico of this region, 

 by the writer, and were named after distinctive fossils: the Tellina 

 ooides zone, the uppermost horizon, the Turritella pescaderoensis zone, 

 the middle horizon and the Actaeonella oviformis zone the lowermost 

 horizon. The oldest fauna ranges through about 350 feet of coarse 

 sediments, the next oldest occurring within the overlying 900 feet of 

 strata and the youngest ranging through the uppermost 300 feet. 



1 Dickerson, E. E., The Martinez and Tejon Eocene and associated formations 

 of the Santa Ana Mountains, Univ. Calif. Publ., Bull. Dept. Geol., vol. 8, pp. 257- 

 274, pis. 26-28, 1914. 



- Packard, E. L., Faunal studies in the Cretaceous of the Santa Ana Moun- 

 tains of Southern California, Univ. Calif. Publ. Bull. Dept. Geol., vol. 9, pp. 137- 

 159, 1 map, 1916. 



