134 PALEONTOLOGY OF CALIFORNIA. 



by three prominent revolving ribs, besides the one at the top of 

 the whorl and one on the lower margin, on the border of the 

 inferior excavation. There is sometimes an additional one inter- 

 polated. Between these ribs are minute revolving lines, some- 

 times obsolete, and very closely placed; four or five between each 

 pair of ribs. These are all crossed by fine lines of growth, regu- 

 larly and broadly curved ; retreating from the suture to about the 

 middle of the whorl, and then descending nearly straight to the 

 base. Under-surface of body whorl slightly convex, and marked 

 by fine revolving lines and strise of growth, or perfectly smooth. 



Length, restored, about 2.5 inches; width of body whorl, .6 

 inch. 



Locality : Chico Creek, Butte County (Div. A.). 



T. UVASANA. 



PL 21, Fig. 92. 



(T. Uvasana, Con. ; Pacific E. E. Eeport, vol. 5, p. 321, pi. 2, fig. 12.) 



Shell moderate in side, very elongated and slender; whorls 

 numerous (about seventeen or eighteen, probably), increasing 

 very gradually in size, convex ; suture impressed. Surface 

 marked by from six to ten distinct, nearly equal, and rather 

 prominent, revolving ribs. No lines of growth, nor intermediate 

 lines were observed, although better specimens may show them. 



Figure, natural size. 



Localities: Along the hills from Bull's Head Point to Clayton, Contra Costa 

 County, and east of the mouth of the Canada do las Uvas, Los Angeles County 

 (Division B.). 



Near Martiiiez, the specimens are embedded in sandstone, and they all appear 

 to have been more or less eroded before fossilization. The species is very common, 

 some strata being almost composed of this one shell. 



