GASTROPODA 



533 



C. annulatum Martin (Fig. 825). Shell 30 nun. long and wide, thin, 

 light brown in color, with purple sutures : California. 



3. MARGARITA Leach. Shell small, thin, conical or globose, with 

 open umbilicus ; whorls rounded and smooth : 24 species, in colder waters. 



Key to the species of Margarita here described : 



0! Shell solid, with 2 or 3 revolving ridges M. OBSCURA 



cr a Shell thin. 



&! Shell with regular spiral lines M. UNDULATA 



6 a Shell yellowish in color M. HELICINA 



M. obscura Couthouy (Fig. 826). Shell small, with a low, conical 

 spire and brownish in color; whorls 5, with 2 or 3 revolving ridges; these 

 with the coarse lines of growth give the shell an indented 

 appearance; length 10 mm.; diameter 12 mm.: Long 

 Island Sound to Labrador, in rather deep water towards 

 the south, but in shallow water towards the north; 

 common. 



M. undulata (Sowerby). Shell thin, conical, brown- 

 ish or red in color, but lusterless ; whorls 6, with short wrinkles near the 

 suture, and with numerous elevated spiral lines at regular intervals; 

 length 7.5 mm. ; diameter 10 mm. : Cape Cod to the Arctic Ocean, from 

 low-water mark to deep water; Europe; common. 



M. helicina (Fabricius). Shell small, 

 thin, light yellowish or pinkish in color, very 

 bright and polished ; whorls 4 or 5, very con- 

 vex; aperture large and circular; length 5 

 mm.; diameter 7.5 mm.: circumpolar, south 

 to Cape Cod and Vancouver; in deep water, 

 but often thrown up on beaches. 



Fig. 826 

 Margarita 06- 

 scura (Try on). 



FAMILY 2. TUEBINIDAE. 



Shell large, spiral, conical, with a large 

 lower whorl and aperture; operculum cal- 

 careous and spiral: 100 species, mostly 

 tropical; about 8 species on the Pacific 

 coast. 



1. TURBO L. Shell turbinate, with 

 rounded whorls ; aperture round : 76 species. 



T. marmoratus L. (Fig. 827). Green snail. Shell 11 cm. long and 

 12 cm. wide; bright green, pearly inside; lip expanded, forming on the 

 columella a wide extension: Indian Ocean; used extensively as an orna- 

 ment and in the manufactures. 



Fig. 827 Turbo marmoratus 

 (Rogers). 



