MARINE MOLLUSCA OF THE UNITED STATES. 87 



Family TURBIXIDJE. 



Shell spiral, turbinated or pyramidal, nacreous inside. Oper- 

 culum calcareous and paucispiral, or horny and multispiral. 



Animal with a short muzzle ; eyes pedunculated at the outer 

 bases of the long and slender tentacles ; head and sides orna- 

 mented with fringed lobes and tentacular filaments. 



Distribution universal ; feeding on sea-weeds. 



The shells are brilliantly pearly under the epidermis and within 

 the aperture. 



Synopsis of Genera. 



Shell turbinated, solid; whorls convex, often grooved or tuberculated ; 

 aperture large, rounded, slightly produced in front ; operculum shelly and 

 solid, callous outside, and smooth, or variously grooved and mammillated, 

 internally horny and paucispiral. TURBO, Linnaeus. 



Shell thin, glohosely depressed, whorls convex, smooth or transversely 

 striated ; aperture nearly circular ; columella ending in a simple point. 



MARGARITA, Leach. 



Shell minute, not nacreous, depressed, few whorled, deeply umbilicated ; 

 peristome entire, nearly continuous, sinuated on its inner side, and 

 slightly so externally ; operculuui shelly, multispiral. 



ADEORBIS, S. Wood. 



Genus TURBO, Linnaeus. 

 Syst. Nat. Edit., x. 761. 1758. 

 1. T. CRENULATUS, Gmelen. Fig. 168. 



Syst. Nat., 3575. 1790. 



Shell ovate, imperforated, sutures of the spire excavated, whorls 

 covered with papillose nodules, convex or slightly angulated in 

 the middle, and ridged, ridges generally squamose, the upper 

 scales being more prominent and erect ; operculum thick, testa- 

 ceous. 



Whitish, with rays or blotches of fawn-color or reddish, pearly 



within. 



North Carolina to West Indies. 



Genus MABGARITA, Leach. 

 .Journ. de Phys., Ixxxviii., 464. 1819. 



The species of this genus are principally inhabitants of north- 

 ern or antarctic seas. They are generally more depressed, 

 smoother, and smaller than Turbo, which is tropical in distribu- 

 tion. 



