20 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
point; the under valve is slightly concave, and the upper valve very 
convexly arched; in front is a small opening, through which the neck of 
the animal passes. Length, about Y? an inch; greatest breadth, equal to 
about % the length. (Gould.) 
Type in United States National Museum. Type locality, lat. 44° N., 
long. 154° W., that is, about 30° west of the mouth of the Columbia River. 
Range. North Pacific Ocean, west of Columbia River. 
Clio occidentalis Dali, 1871 
American Journal of Conchology, 7:140. 
Shell tricarinated, transversely striated, sides a little concave, tip 
straight. Long., .6; lat., .45 in. (Dali.) 
Type in United States National Museum. Type locality, North Pacific, 
off coast of California, in lat., 33° N., long., 130° W. 
Range. Northeast Pacific between lat. 30° and 50° N. off the 
Farallon Islands. 
Genus STYLIOLA Lesueur, 1826 
Shell slender, conical, pointed, straight or curved. Fins rather narrow, 
truncate, with small tentacles projecting from their dorsal edges, and 
rudiments of the mesopodium on their surface; mantle-margin with a 
spiral process on the left side. M. Rang states that he has seen these 
Pteropods clustering round floating seaweed. (Tryon, Structural and 
Systematic Conch ology .) 
Example. Styliola subulata Quoy. 
Styliola falcata Gould, 1852 
Mollusca and Shells of the United States Exploring Expedition (under Wilkes), 490; 
PI. 51, fig. 608. 
T. elongato-conica, valde recurva; apertura circularis. (Gould.) 
Shell very strongly recurved, forming nearly a quarter of a circle; 
aperture circular. Length, not over half an inch. (Gould.) 
Type in United States National Museum. Type locality, Northeast 
Pacific. 
Range. Northeast Pacific west of Oregon. 
Family CYMBULLIDAE 
Genus COROLLA Dali, 1871 
Like Tiedmannia, but with the body pendant below, unattached to the 
pinnae, ovoid, constricted above; oesophagus produced, oral aperture 
trumpet-shaped, produced into two points. Pinnae forming a single disk 
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