304 LITTORINID^. 



ture oblique, semi-circular, angles a little rounded; outer lip sharp; 

 inner lip straight, like a rounded white rib, broadest and twisted 

 behind ; at the side of it is a narrow, crescentic, white 

 Fig. 574. gpace, bounded externally by the continuation of the sharp 

 lip, along which a groove runs, terminating in a deep um- 

 bilicus ; operculum horny, sub-spiral. Length, one fifth of 

 an inch ; greatest breadth, one fourth of an inch ; diver- 

 gence, ninety-five degrees. 

 A few specimens of this shell have been collected at different 

 times on Chelsea Beach. It is probably floated ashore on sea-weed. 

 Ocean House, Swampscott (^Haskell) ; fossil, Montreal (^Dawsori) ; 

 whole New England coast {Stimpson). 



It is sufficiently distinct from specimens of Tm-bo pallidulns, sent 

 me from Europe for comparison, by its narrower channelled space, 

 and its smaller umbilicus ; and more especially by the aperture not 

 being at all trumpet-shaped, or angular, as in that shell. They are 

 so nearly alike, however, that it is very difficult to delineate, either 

 by description or figures, distinctions which are very obvious on in- 

 spection. I have received it from Dr. Loven, labelled, doubtfully, 

 L. Montag-ui, Turton. 



Genus LITTORINA, Ferussac. 1821. 



Shell thick, top-shaped, spire of a few rounded whorls ; aperture 

 entire, rounded-ovate, large ; outer lip sharp, inner lip somewhat 

 flattened ; lips not continuous posteriorly ; operculum horny, spiral. 



Littorina rudis. 



Fig. 165. 



Shell strong and coarse, volutions convex and well defnied, with revolving 

 ridges; pillar flattened, prolonged so as to form an angle in front; color yel- 

 loAvish. 



Turbo rudis, Donovan, Brit. Shells, i. t. .33, fig 3 (1800). —Montagu, Test. Brit. 304. 



— Turton's Lin. iv. 480; Conch. Diet 197. — Chemn. Conch, v. t. 185, fiff. 18.i5. 



— Maton and Rackett, Lin. Trans, viii. 1.59, t. 4, figs. 12, 13. — Wood, Index, pi. 

 30, fis. 7. — Lam. An. sans Vert. 1st ed. vii. 49. — Fleming, Brit. Anim. 298. 



Tw-ho ohUrjatns, Sat, Joiirn. Acad. Nat. So. ii. 241. 



Littorina rudis, Gould, Inv. 1st ed. 257, fig. 165.— De Kay, N. Y. Moll. 104, pi. 5, fig. 

 103. — Stimpson, Check List-;, 5. 



Shell broad-ovate, strong and coarse, generally yellowish or ash 

 colored, sometimes orange or olive, for the most part of one uniform 



