Page:American Seashells (1954).djvu/472

2 to 4 inches in length, very similar to A. alba, but with a more chalky shell, never with orange color, interior usually pustulose, and the long, an- terior muscle scar juts away from the pallial line at an angle of about 30 degrees instead of paralleling it as in alba. An uncommon species, commonly confused with alba. It lives down to 50 fathoms but at times is washed ashore. A, schrammi Crosse is this species. Genus Codakia Scopoli 1777 Shell large, orbicular, moderately compressed. Hinge of right valve with a prominent anterior lateral which is typically close to the cardinals (an an- terior, a posterior and a middle cardinal). Hinge of left valve with a large double anterior lateral, only 2 cardinals, and with a small, double posterior lateral. Subgenus Codakia s. str. Codakia orbicularis Linne Tiger Lucina Plate 38d Florida to Texas and the West Indies. 2 % to 3 % inches in length, slightly less in height, well-compressed, more or less orbicular in outline, thick and strong. Beaks and /4 inch of subsequent growth smoothish. Remainder of the shell roughly sculptured by numerous coarse radial threads which are crossed by finer concentric threads. This commonly gives the radial ribs a beaded appearance. Exterior white. Inte- rior white to pale-lemon, commonly with a rose tinge on the ends of the hinge or along the margins of the valves. Lunule jusf in front of the beaks is deep, heart-shaped, small and nearly all on the right valve. A common trop- ical species. Do not confuse with C. orbiculata. Codakia costata Orbigny Costate Lucina North Carolina to southeast Florida and the West Indies. /4 inch in length, variable in shape, but usually orbicular, quite obese, white to yellowish in color. With fine radial ribs, usually in pairs which are crossed by very fine concentric threads. Beaks also* with this sculpturing. Lunule small, indistinct, lanceolate, slightly more on the right valve. Com- pare its poorly defined lunule with those of orbicidaris and orbiculata. Mod- erately common offshore on sandy bottoms. Subgenus Epilucina Dall 1901 Codakia californica Conrad Californian Lucina Plate 31C Crescent City, California, to Lower California.