56 AMERICAN MARINE CONCIIOLOGY. 



Genus VOLVA, Bolten. 

 Museum. 1798. 



I. y. uxiPLiCATA, Sowerby. Fig. 93. 



(Ooulura.) Proc. Zool. Soc, 135. 1848. 



Shell narrowl}' oblong, rather thin, whitish or orange-rose, ex- 

 tremities rather produced, blunt, back transversely minytely stri- 

 ated ; lip moderately thickened, flexuous, widely sinuated at the 

 lower part; columella plicate above. 



South Carolina, southwards. 



Order I. PROSOBRANCHIATA. 



Section B. Holostomata. Sea-snails. 

 Shell spiral or limpet-shaped ; rarely tubular or multivalve ; 

 margin of the aperture generally entire ; operculum horny or 

 shell3', usuall}' spiral. Animal with a short non-retractile muzzle; 

 respirator}^ siphon wanting, or formed by a lobe developed from 

 the neck ; gills pectinated or plume-like, placed obliquely across 

 the back, or attached to the right side of the neck ; neck and sides 

 frequently ornamented with lappets and tentacular filaments. 

 Mostly phytophagous. Aperture channelled in front, with a less 

 distinct posterior canal. 



I. Aperture entire. Shell globular or turhiniform. 

 Family I. Naticid^. Shell globular, few-whorled ; spire small, 

 obtuse ; aperture semilunar; lip acute; pillar often callous. 



II. Shell elongated. 



Family II. Pyramidellid^e. Shell spiral, turreted ; nucleus 

 minute, sinistral ; aperture small; columella sometimes with one 

 or more prominent plaits ; operculum horny, imbricated ; nucleus 

 internal. 



Family III. Cerithiad^. Shell spiral, elongated, many-whorled, 

 frequently varicose ; lip generally expanded in the adult ; ojiercu- 

 lum horn}' and spiral. 



Family V. TuRRiTELLiDiE. Shell tubular or spiral, upper part 

 partitioned off; aperture simple; operculum horny, many whorled. 



Family YI. Littorinid.^. Shell spiral, turbinated, or depressed, 

 never pearly ; aperture rounded ; peristome entire ; operculum 

 horn}', pauci-spiral. 



Family IX. Turbinid^. Shell spiral, turbinated, or pyramidal, 



7D 



