CRETACEOUS FOSSILS. 109 



heavy callus, a portion of which is developed into a large trian- 

 gular mass, which nearly fills the umbilicus; across this and 

 below the middle is a well-marked transverse groove. Umbilicus 

 broad, but nearly closed. Surface marked by lines of growth. 



Figures, natural size. 



Locality: Alizos Creek, near Fort Tejon. 



This species closely resembles Lunatia Hornii in its upper aspect, so much so that 

 the differences would hardly appear of specific value. It differs, however, in 

 being more oblique above, less regularly globose, and in the callus, which at once 

 separates it from the genus Lunatia. 



NATICINA, Gray. 



N". OBLIQUA, II. S. 

 PI. 21, Fig. 112. 



Shell small, oblique; spire slightly prominent; whorls four, 

 rapidly increasing in size ; suture faintly canaliculate. Surface 

 marked by numerous compound revolving lines, minutely waved 

 laterally, and showing a tendency to an alternation of larger and 

 smaller ones; these are crossed by irregular lines of growth, 

 which completely encircle the whorls, and are most distinct and 

 crowded in the umbilicus. Aperture patulous, acute behind. 

 Inner lip slightly thickened, and forming a small incrustation on 

 the preceding whorl. Umbilicus moderate in size. 



Figure, nearly twice natural size, linear. 



Locality : Northeast of Martinez (Division B.) ; also from Canada de las Uvas 

 and vicinity. 



AMAUROPSIS, Morch. 



A. OVIFORMIS, n. s. 

 PI. 19, Fig. 63. 



Shell ovoid; spire rather elevated; whorls six, rounded ; suture 

 slightly channelled. Aperture moderate, acute posteriorly, ex- 



