1915] 



Clark: Fauna of the San Pablo Group 



485 



Occurrence. — This species is found in the upper beds of the San 

 Pablo Group in the region of Kirker Pass, University of California 

 locality 1482. It is here associated with Cyrena calif omica Gabb and 

 Trophon pondcrosum Gabb. 



CEEPIDULA PABLOENSIS, n. sp. 

 Plate 70, figures 1, 2, arid 3 



Shell elevated, heavy ; base broadly ovate to subcircular ; upper 

 surface broadly arched; apex nearly central, elevated considerably 

 above the posterior edge .of aperture. Sides of shell nearly vertical, 

 the right side being slightly higher than the left. Deck concave similar 

 to that of C. prince ps Conrad. Surface sculptured by rather coarse 

 radiating ribs, separated by narrow interspaces ; surface also covered 

 by fairly coarse concentric lines of growth. 



This species somewhat resembles in outline C. aclunca Sowerby, a 

 Recent form, which also occurs in the San Pablo Group ; it differs in 

 the prominent radiating ribs, larger size, the concave anterior edge 

 of the deck, and the beaks are not so hooked. 



Occurrence. — In the Upper San Pablo Group to the southeast of the 

 town of Walnut Creek, University of California locality 313. 



CALYPTKAEA DIABLOENS1S, n. sp. 

 Plate 70, figure 9 



Shell high, rather large and heavy for this genus ; apex subacute 

 and central; sutures obscurely appressed; surface covered by about 

 21 to 25 heavy, broad, rounded, slightly oblique longitudinal ribs with 

 deep V-shaped interspaces, the interspaces being much narrower than 

 the tops of the ribs, the ribbing extending uninterruptedly from one 

 whorl to the next. 



This species resembles somewhat the specimen figured by Arnold as 

 Trochita costcllata Conrad (Bull. U. S. G. S. no. 309, p. 236, pi. 

 XXXII). C. diabloensis is a larger and higher form. The ribbing is 

 more prominent, heavier and closer together. 



C. diablocnsis was listed by the writer in his paper the "Neocene 

 Section at Kirker Pass on the North Side of Mount Diablo," Uni- 

 versity of Calif. Publ. Bull. Dept. Geol., vol. 7, no. 4, p. 54, as C. cos- 

 tcllata Conrad. Further work and better material shows that the de- 

 termination was wrong. 



