488 University of California Publications in Geology [Vol. 8 



NATICA (NEVERITA) ARNOLDI, n. sp. 

 Plate 68, figures 13 and 15 

 Shell heavy, ovate in longitudinal oiitline; spire somewhat variable 

 in height ; apex acute. Whorls four to five ; sutures strongly appressed ; 

 body whorl nearly three times as high as spire. Outer lip sharp ; inner 

 lip completely covered by a large elongate callus which is wider pos- 

 teriorly than anteriorly. On the larger specimens the callus covers 

 the umbilicus completely, on some of the smaller specimens the 

 umbilicus is partially open. Surface smooth except for incremental 

 lines ; base of body whorl narrow, slanting down obliquely to the 

 umbilicus. 



This species differs from N. diabloensis, n. sp., which is found in 

 the same horizon, in that the base is narrower, the mouth is more 

 elongate ; the sutures are more strongly appressed ; the umbilicus is 

 usually entirely covered by the elongate callus, while the umbilicus of 

 N. diabloensis is entirely open ; the spire is slightly higher and the 

 body whorl is not so ventricose. 



Dimensions. — Height, 39 mm. ; greatest width of body whorl, about 

 28 mm. ; height of body whorl. 29 mm. 



Occurrence. — Upper San Pablo Group, University of California 

 localities 505, 1270 and 1229. 



NATICA (NEVERITA) PABLOENSIS, n. sp. 

 Plate 68, figures 12 and 14 



Shell large, globular, thick, heavy. Whorls three; spire low, in- 

 conspicuous, so much so that the top of the shell is very broadly 

 rounded or flattened. Sutures very strongly appressed. Body whorl 

 large with sides flattened, tending to form an obscure shoulder on the 

 upper part of the whorl. Surface covered by fairly heavy lines of 

 growth. Aperture semi-lunar ; outer lip thin ; inner lip and umbilicus 

 covered by a broad, flat, faintly grooved callus. Umbilicus completely 

 covered by callus. 



The writer has examined over a dozen specimens of this species 

 on which the callus was very well preserved; only on two of these 

 could the anterior groove be seen and on those it showed only very 

 faintly. 



N. pabloensis is very similar to N. ocoyana Conrad, a species very 

 common in the Lower Neocene of the southern part of the state. Both 

 of these species are closely allied to N. recluziana Petit, a Recent 



