CORBULIDAE 457 



% of an inch in length, % as high, moderately thin-shelled and glossy. 

 Beaks high, curled under and pointing anteriorly. Right valve subtrigonal 

 in shape, very obese and with strong, concentric ridges. Left valve more 

 elongate, smaller, less obese and with numerous but weaker ridges. Color 

 white, but some may be tinted with rose near the margins. Uncommonly 

 dredged from 12 to 250 fathoms. Live specimens very rare. This is C. dis- 

 parilis of authors. 



Genus Corbula Bruguiere 1792 



Small, thick shells characterized by one valve (commonly the right) 

 being larger than the other. Posterior end commonly rostrate. Resilium 

 and ligament internal. The genus Aloidis Aliihlfeld was in current use until 

 recently. 



Corhila contracta Say Contracted Corbula 



Cape Cod to Florida and the West Indies. 



^4 inch in length, oblong, moderately to strongly obese. Both valves 

 about the same size, except that the posterior, ventral margin of the right 

 valve overlaps that of the left. The numerous, poorly defined, concentric 

 ridges on the outside of the valves extend over the posterior, radial ridge on 

 to the posterior slope. The left valve has a V-shaped notch in the hinge 

 just anterior to the beak. Color dirty-gray. A common shallow-water 

 species. 



Corbula dietziana C. B. Adams Dietz's Corbula 



North Carohna to southeast Florida and the West Indies. 



% to ^ inch in length, like contracta, but larger, thicker-shelled and 

 pinkish inside. The ventral margins are blushed or rayed with carmine-rose. 

 Microscopic threads numerous between the few coarse, concentric ridges. 

 Compare with the smaller and more comprecsed barrattiana. Commonly 

 dredged offshore in the Miami region. 



Corbula nasuta Say Snub-nose Corbula 



North Carolina to both sides of Florida and the West Indies. 



%6 to % inch in length, oblong, obese and strongly rostrate at the pos- 

 terior end. The posterior end looks as if it had been severely pinched. Right 

 valve considerably larger than the left. Margins of valves with a thick border 



