96 



EAST COAST MARINE SHELLS 



PI. 36, Fig, 6 



Nova Scotia to Florida; Texas 



CREPIDDLA GLADCA CONVEXA Say. Convex Slip- 

 per. Apex obliquely beaked; shell convex 

 or high backed, otherwise as in C. glauca. 

 Length 14 mm. or more. 



C. glauca and its variety are very 

 closely related to C. fornicata. 



PI. 69, Fig. isr 



Nova Scotia to Florida; Texas 



CREPIDULA PLANA Say (C. ungulformis Lam.). 

 Flat Slipper. Shell ovate, flat, concave, 

 or convex, thin, transparent, white; apex 

 minute, turned a little to one side; in- 

 terior brilliantly polished and iridescent; 

 diaphragm less than one-half length of 

 shell. Length 30 mm. The radula is shown 

 on PI. 68, Fig. IS. 



This mollusk lives attached often 

 Inside dead shells inhabited by hermit- 

 crabs. It is frequently curved to conform 

 with the substance to which attachment Is 

 made. The size and shape vary accordingly. 



PI. 36, Fig. 14 



PI. 69, Fig. 26 



Prince Edward Island to Texas 



CREPIDULA ACULEATA Gmelin, Thorny Slipper. 

 Exterior covered with radiating prickly or 

 spiny ridges; often with brown rays upon a 

 white or yellowish base; interior frequent- 

 ly spotted or rayed with brown; shelf white. 

 Length 25-37 mm. 



PI. 36, Fig. 2 



Cape Hatteras, North Carolina to 



West Indies, California 



Family Truncatellldae 



Foot short and rounded; nead bi- 

 lobed. Shell minute, shining, cylindrical, 

 apex truncated; operculum subspiral. 



These little shells are found under 

 stones, wood, and seaweed between tide 

 marks. They often remain weeks out of the 

 water. 



GENUS TRUNCATELLA Rlsso 1826 

 (LOOPING SNAILS) 



TRUNCATELLA BILABIATA Pfeiffer, Whorls 4.5- 

 5, convex, the last one no longer than the 

 others; peristome double, outer one white 

 and heavy. Length 5.5 mm. 



PI. 36, Fig. 13 



Florida; Cuba; West Indies 



TRUNCATELLA CARIBAEENSIS Sowerby. Shell 

 subcylindrical In adult state; amber color 

 with delicate barely curved ribs, often be- 

 coming fainter in center of whorls; 3.5-4 

 whorls, slightly rounded, the last Indis- 

 tinctly keeled; aperture oval, inner lip 

 thickened and pressed into the last whorl, 

 outer lip reflexed. Length 7 mm. 



PI. 36, Fig. 11 



Florida; West Indies 



TRUNCATELLA CARIBAEENSIS PULCHELLA Pfeiffer. 

 Light horn or amber color; lightly ribbed, 

 ribs not elevated; whorls 4-4.5, peristome 

 simple, expanding with slight ridge at 

 right extremity. Length 5 mm. 



PI. 36, Fig. 12 



Florida; West Indies 



Family Rissoildae 



Shell small, often minute, more or 

 less umbillcated; lip rounded; sculpture 

 variable. These little mollusks live upon 

 algae, oysters. Pinna shells and beneath 

 sponges. 



GENUS RISSOA Freminville 1814 



Shell more or less oblong, often 

 thick, white or yellowish; operculum corne- 

 ous. In this and the genus Rissoina the 

 animal is remarkably active and bold. It is 

 provided with long, slender tentacles, the 

 eyes being placed near their bases. They 

 quickly spin a byssal thread to use as a 

 ladder when detached from some solid ob- 

 ject. 



There are hundreds of known species 

 and probably as many more awaiting discov- 

 ery. They range to a depth of 100 fathoms 

 but are most abundant in shallow water. 



RISSOA EXARATA Stimpson. Shell minute. Im- 

 perforate; whorls five, evenly spaced; 

 axial ribs elevated; lip thickened; aper- 

 ture small. Length 2.7 mm. Depth range 

 3-107 fathoms. 



Bay of Fundy to North Carolina 



Family Rlssoinidae 



Shell turriculated; many, somewhat 

 convex, whorls; apex mammillar; peristome 

 interrupted by canal below. 



