1915] 



Clark: Fauna of the San Pablo Group 



487 



Mouth semilunate with fairly heavy triangular callus in the posterior 

 angle of the inner lip ; umbilical opening rather narrow and elongate. 



This species somewhat resembles N. lewisii Gould, a Recent form 

 on the West Coast; it differs in that the spire is slightly more acute 

 and it lacks the shallow, spiral groove, which is seen on N. lewisii 

 just below the suture. The callus on the inner lip of N. diabloensis is 

 heavier than on N. lewisii and the umbilical opening is longer and 

 narrower. 



It is very doubtful whether N. lewisii extends much below the 

 Pleistocene. It is, however, found in nearly all the old California 

 Miocene and Pliocene check-lists. There have been at least four or 

 five species listed as N. lewisii. 



Dimensions. — Height, 49 mm. ; greatest width of body whorl, 

 35 mm. 



Occurrence. — In the Upper San Pablo, associated with Astrodapsis 

 tumidus, Tivela gabbi, etc. ; University of California locality 1947. 

 Also in the upper Santa Margarita to the north of Coalinga. 



NATICA (EUSPIRA) KIEKENSIS, n. sp. 

 Plate 69, figures 4 and 9 



Shell heavy ; base broad ; apex acute ; spire about half as high as 

 the body whorl. Sutures strongly appressed, the appressed part of 

 the lower whorl sometimes extending as much as half way up to the 

 next suture. On many of the specimens the appressed part of the 

 body whorl has been weathered away ; the suture then is strongly de- 

 pressed, giving a subtabulate effect to the whorl. Surface of shell 

 smooth except for somewhat irregular lines of growth. Peristome 

 semilunate. A heavy, ungrooved triangular callus on the inner lip. 

 which is broader on the upper angle of the mouth, spreading out on 

 the base of the whorl. Umbilicus large, open. 



N. Mrkensis differs from N. diabloensis, n. sp., found in the Upper 

 San Pablo in that the body whorl is broader in proportion to the 

 height of the shell; the base is broader and flatter; the sutures are 

 more strongly appressed and the umbilical opening is much broader 

 and more open. 



Dimensions. — Type specimen : height, 36 mm. ; greatest diameter of 

 body whorl, about 33 mm. 



Occurrence. — University of California localities 100, 183, 463, 752. 

 So far this species has not been found in the Upper San Pablo. It is 

 common in the Lower San Pablo and the Scutella breweriana zone. 



