78 AMERICAN MARINE CONCIIOLOGY. 



impressed lines ; suture well impressed ; body-whorl with about 

 sixteen costae. 

 Length 13 mill. 



Massachusetts, southwards. 



7. S. bureaus, Beck. Fig. 143. 

 Acirsa borealis, Morch. 1841. 



8. Eschriehtii, Moller. 1845. 



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

 ten, convex, with numerous revolving stria-; the upper whorls 

 with slight transverse undulations or faint costffi, which are want- 

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

 roundish, efl'use, and slightly angulated in front. 



Length 1 9, diam. (',.5 mill. 



Dredged, ten to forty fathoms. 



Maine, northward*. 



Family VI. LITTORINIDJ]. 



Shell spiral, turbiniform or depressed, never pearly ; 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 alga?. Distribution uni- 

 versal, inhabiting sea or brackish water. 



Synopsis of Otnera. 



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



acute ; columella rather flattened, imperforate ; operculum paucispiral. 



LlTTOBINA, Ferussac. 



Shell obicular, depressed; umbilicus wide ami deep; aperture rhombic; 

 peristome thin ; operculum horny, subspiral. 



A ite 1 1 it ki "I'n mc a, Bolten. 

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



umbilical fissure ; operculum paucispiral. Lacuna, Turton. 



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

 smooth, ribbed or cancellated ; aperture rounded; peristome entire, con- 

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



Rissoa, Fremcnville. 

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

 entire ; operculum annular, regular, with an internal procesa. 



Kissoella, Gray. 



