96 LITTORINIDiE. 



individuals are rather strong, a little glossy, more or less 

 translucent, and either uniform white (often, however, witli 

 a ferruginous tinge) or marked behind the outer lip with 

 two rufous or tawny stains, that severally form the com- 

 mencement of a subsutural and inframedial zone. The 

 exterior is densely and strongly striated with raised spiral 

 lines, and (except in the variety Candida) is partially 

 adorned with longitudinal pliciform ribs, that in general 

 are rather distant and oblique, but vary considerably in 

 these respects. The ribs even upon the smaller turns 

 seldom reach the lower suture, and upon the two larger 

 ones extend but a little distance from the upper separating 

 line from whence they emanate. There are six and a half 

 ventricose whorls, divided by a deep biit simple suture, 

 and oftentimes placed so irregularly that the shell appears 

 distorted. The apex is blunt ; the next two coils are small 

 in proportion to the penult, which is likewise swollen : the 

 body is, in general, almost as narrow as the preceding 

 Wiiorl, and merely occupies from one third of the total 

 length in the produced forms, to two fifths in the abbre- 

 viated ones ; its basal declination is rounded and gradual. 

 The aperture is suboval, but contracted above, and smooth 

 within ; it occupies from about one third to three eighths 

 of the entire length ; its peristome is continuous, the 

 parietal enamel being for the most part thickly spread. 

 The projecting outer lip is strong but not marginated 

 behind ; it is much arcuated, and at the front extremity is 

 somewhat pouting and well rounded. There is no umbi- 

 lical chink, the pillar lip, though well defined, being usually 

 apprcssed. The length of our largest example is only the 

 seventh of an inch, and its breadth about four-fifths of a 

 line. 



A slender, almost cylindrical variety, which frequently 



