118 PALAEONTOLOGY OF CALIFORNIA. 



whorl bearing three ribs, one at tbe extreme edge, one above, 

 and tlie third below. Mouth rounded, subtriangular. Umbilicus 

 broad, margin strongly crenulated. Upper surface marked only 

 by lines of growth ; lower surface grooved by extension of the 

 crenulation of the umbilical margin, and by variable revolving 

 lines. 



Figures, about three times natural size; Fig. 224 b, is from the under surface 

 of the body whorl. 



Locality: Three specimens were collected by Dr. Horn near Fort Tejon. 

 (Div. B.) 



This species diflfers from A. cognata in the lower spire, convex upper surface, 

 less acute angle, the position of the marginal ribs, and much smaller size. 



A. INORNATA, U. S. 

 PI. 20, Fig. 73. 



Shell robust, conical; spire elevated; whorls five, flattened on 

 the sides, compressed or channelled above, subangular on the 

 margin ; suture impressed. Surface usually only marked by lines 

 of growth. Body whorl channelled above, angulated on the 

 margin, with sometimes a slight depression below the angle. 

 Lower margin rounded. Under surface slightly convex. Um- 

 bilicus narrow, but open the whole length of the spire ; internally 

 striate. Mouth rounded, subquadrate. 



Figure, natural size. 



Localities: Abundant in the hills southwest of Martinez. A single specimen 

 was found at Tuscan Springs, Tehama County, by Dr. Veatch. Only found in 

 Division A. 



One specimen from Martinez shows faint revolving lines on the outside of the 

 whorls. 



MARGARITELLA, Meek and Hayden. 



M. CRENULATA, 11. S. 

 PI. 20, Fig. 74. 



Shell minute, turbinate ; spire proportionally not so elevated 

 as in the preceding species; whorls five; suture channelled. 



