12 



Land and fresh- water shells of n. a. [part i. 



Microscopic revolving lines have been detected on some speci- 

 mens. There is a form of a dark reddish-brown color, with one 

 white band at the periphery, and the same color at the base 

 around the umbilicus. 



ayersiana, Newcomb. — Shell umbilicafed, glohosely-convex, 

 rather thick, of a de-nd white with a narrow revolving 

 brownish band, with rough oblique incremental strise 

 deeply cut by coarse revolving lines ; whirls seven, 

 rather convex, the last globose, descending in front; 

 spire elevated ; umbilicus small ; aperture oblique, 

 subcircular, banded within ; peristome simple, its 

 ends joined by a light callus, that of the columella 

 widened, reflected over and half concealing the um- 

 bilicus. Greater diam. 21, lesser 19 ; height 12i mill. 



Helix ayersiana, Newcomb, Proc. Cal. Acad. Nat. 



Sci. II, 103 (18(51). 

 Aglaja ayersiana, Tkyox, Am. .Tourn. Conch. 11, 312 



(1866); III, pi. xi, f. 28 (1867). 



Helix ayersiana. 



Northern Oregon {Neiccomh) ; Santa Cruz 

 Island, Cal. (J". G. Cooper). 

 My description and figure are drawn from an authentic specimen. 



Fig. 121. 



Helix strigosa, Godld. — Shell broadly umbilicated, orbicular, 

 slightly, and about equally, convex above and be- 

 neath, surface irregular, and roughened above by 

 indentations and coarse lines of growth, and by occa- 

 sional fine revolving lines ; smoother and shining 

 beneath ; color ashy gray, somewhat mottled with 

 dusky, or altogether ru.sty brown above, with, usu- 

 ally, a single, faint, revolving band on the middle of 

 each whirl, and often with numerous bands, unequal 

 in size and distance, beneath ; whirls five, moder- 

 ately convex, the last one carinated at its commence- 

 ment, and deflexed ; aperture very oblique, circular ; 

 peristome simple, acute, almost continuous, termina- 

 Stlix strigosa. tions approaching, joined by thick callus, that of the 



