496 University of California Publications in Geology [Vol. 9 



Occurrence. — University of California Locality 2225, Oroville 

 South Table Mountain, Butte County, California. 



NATICA GESTERI, n. sp. 

 Plate 38, figure 6 



Shell small, high, with five whorls. The spire, one-fourth the shell- 

 length, has slightly convex, smooth whorls. The body-whorl which is 

 unusually elongate for this genus is gently convex. Aperture 

 semilunar; outer lip simple; inner lip incrusted; umbilicus small, 

 narrow, resembling that of Lunatia hornii Gabb. 



The greater length of this species distinguishes it from other 

 naticoid forms of the Tejon. 



Named for Mr. Clarke Gester who discovered this species. 



Dimensions. — Length, 15 mm.; width of body-whorl, 9 mm. 



Occurrence. — University of California Locality 1817. 



NYCTILOCHUS THUNANI, n. sp. 

 Plate 41, figures 8a, 8b 



Shell fusiform, with moderately high spire ; whorls seven, the first 

 two whorls being smooth ; third whorl decorated with ten swollen 

 nodes which extend from suture to suture ; fourth, fifth, sixth and 

 seventh whorls are decorated by similar elongate nodes which become 

 decidedly .sinuous upon the body-whorl ; suture sinuous, distinct ; 

 body -whorl has a wide mouth which is narrowed in advance ; canal 

 recurved, twisted ; outer lip thickened and denticulated on interior ; 

 inner lip covered by a slight callus. Numerous well-marked revolving 

 lines which alternate regularly in size, cover all the last five whorls ; 

 these lines are crossed by finer axial lines which vary but slightly. 



This species resembled Nyctilochus whitneyi (Gabb), but its spire 

 is shorter, mouth wider, body-whorl stouter and the spiral lines al- 

 ternate regularly in size. There are occasionally as many as four 

 minor spiral lines between major spiral lines on N. whitneyi and the 

 major ones are more strongly set off than in N. thunani. 



Named in honor of Mrs. Fred Thunan of Oroville, who presented 

 the type to the University of California. 



Dimensions. — Height, 19 mm. ; width of body-whorl, 12 mm. 



Occurrence. — University of California Locality 2225, about one 

 mile north and three degrees west of Butte County Hospital, Tejon of 

 Oroville South Table Mountain. 



