78 AMERICAN MARINE CONCHOLOGY. 



impressed lines ; suture \^•ell impressed ; body-whorl with about 

 sixteen costa?. 



LeuiTth 13 mill. 



Massachusetts, southicards. 



1. S. I30REATJS, Beck. Fig. 143. 

 Acirsa horeijlis, ^lorch. tS41. 

 ,S. Eschrichtii. MoWcr. 1S45. 



Shell white or pale flesh-color, elongated, turreted, acute; whorls 

 ten, convex, with numerous revolving striiv; the upper whorls 

 with slight transverse undulations or faint costiv, wliich are want- 

 ing on the lower ones; last whorl slightly carinated ; aperture 

 roundish, effuse, and slightly angulated in front. 



Length 10, diam. 6.5 mill. 



Dredged, ten to forty fathoms. 



Maine, tiortJi wards. 



Family YI. LITTOKIXID.E. 



Shell spiral, turbiniform or depressed, never pearl3' ; aperture 

 rounded ; peristome entire; operculum horny, paucispiral. 



Animal with a muzzle-shaped head; eyes sessile at the outer 

 bases of the tentacles; tongue denticulated; branchial plume 

 single; foot with a linear duplication in front and a groove along 

 the sole ; mantle with a rudimentary siphonal canal; operculum 

 lobe appendaged. Littoral, feeding on algj^. Distribution uni- 

 versal, inhabiting sea or brackish water. 



Synopsis of Genera. 



Shell turbiuatoii, thick, pointed, few-whorled; aperture rounded; outer lip 



acute ; columolla rather flattened, imperforate ; operculum paucispiral. 



LiTTORiNA, Ferussac. 



Sliell obioular, depressed ; umbilicus wide and deep ; aperture rhombic ; 

 peristome thin ; oporcuUim horuy, subspiral. 



Architecto^ica, Bolteu. 



Shell turbinated, thin; aporlure semilunar; columella flattened, with an 



umbilical fissure ; operculum paucispiral. Laccxa, Turtou. 



Shell minute, thick, white or horny ; conical, pointed, many-whorled ; 

 smooth, ribl>ed or cancellated ; aperture rounded ; peristome entire, con- 

 tinuous ; outer lip slightly expanded and thickened ; operculum subspiral. 



RissoA, Fr^menville. 

 Shell minute, thin, subglobose or conical, transparent ; peristome thin, 

 cutue ; operculum iumular, regular, with an internal process. 



RissOELLA. Grar. 



