538 MOLLUSCA 



N. pusilla Say (Fig. 832). Shell thin and small, often streaked 

 with brown; callus white, and pressed laterally into the umbilicus, which 

 is nearly closed; length 6 mm.; diameter 5 mm.: Massachusetts to west 

 Florida; common in shallow water. 



N. (Polynices Montfort) immaculata Totten. Shell 

 solid and small; umbilicus rounded and deep, but little 

 covered by the small callus; color yellowish, and white 



Fig. 832 beneath ; length 7 mm. ; diameter 5.5 mm. : Long Island 



Natica pusilla ~ ,. _ ._ ,. _ ."' ' V n 



(Verriii). Sound to the Gull or St. Lawrence, in shallow water; 



often common. 



N. groenlandica Holier. Shell small, smooth, glossy, bluish-white, 

 with minute revolving lines; 12 mm. long; 11 mm. in diameter; callus 

 white, nearly filling the umbilicus, leaving only a narrow, curved open- 

 ing: Cape Cod, northwards. 



N. clausa Broderip. Shell small, whitish or brownish, without 

 revolving lines; 15 mm. long; 13 mm. in diameter; callus white, com- 

 pletely filling the umbilicus; operculum calcareous: circumpolar, south 

 to Cape Cod and Vancouver; common. 



2. SIGARETTJS Lamarck. Shell flat and ear-shaped, with a minute 

 spire and an enormously expanded aperture; mantle large, partly 

 or entirely covering the shell; operculum minute, horny; propodium 

 enormously developed, used for 



burrowing : 100 species, 3 on the 

 Atlantic coast. 



S. perspectivus Say (Fig. 

 833 ) . Shell oval, flattened, white, 

 smooth, and polished; 37 mm. 

 long ; 30 mm. wide : New Jersey 



to Florida; common in shallow "VftGS^^ 

 water. 



3. VELUTINA Blainville. Shell small, thin, covered with a velvety 

 periostraeum ; spire minute; lower whorl large, with a circular aperture; 

 no operculum: 2 species, on the Atlantic coast. 



V. Isevigata (L.) (V. haliotoidea Fabricius) (Fig. 834). Shell very 

 thin and fragile, transparent, pinkish; whorls 3; length 12 mm.; diam- 

 eter 10 mm. : Cape Cod, northwards. 



FAMILY 2. CAPULIDAE. 



Shell conical, flat, or boat-shaped, with scarcely any spiral, or 

 none at all; interior with a shelf, variously formed, to which the 

 adductor muscles are attached; no operculum; head distinct, with a 



