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378 shell. Occasionally the ribs are less strongly developed. Common from just offshore to 30 fathoms. Superfajnily CARDITACEA Family CARDITIDAE Genus Cardita Bruguiere, 1792 Shell small, thick, radially ribbed, quadrate, with a slight ventral gape and having a byssus. The animal has a marsupium to contain its eggs. Pos- terior right cardinal usually absent or almost so. This appears to be the accepted use of Cardita according to Winckworth, Chavan, Lamy and Dall. Subgenus Carditamera Conrad 1838 Carditaviera has shells which are more elongate and have strong lateral teeth. Cardita floridana Conrad Broad-ribbed Cardita Plate 30a Southern half of Florida and Mexico. I to I /4 inches in length, about half as high, elongate, inflated, solid and heavy. Surface with about 20 strong, rounded, raised, beaded, radial ribs. In live material, the gray periostracum obscures the color of the shell. Ex- terior whitish to gray with small bars of chestnut color on the ribs arranged in concentric series. Interior white with a small light-brown patch above the two muscle scars. Beaks close together. Lunule small, very deeply in- dented under the beaks. Ligament moderately large, visible from the out- side. Very common on the west coast of Florida where it is washed ashore. Used extensively in the jewelry business. Cardita gracilis Shuttleworth is doubtfully recorded from Florida but is known from Mexico to Puerto Rico. It is quite elongate, narrow at the anterior end, with larger, smoothish ribs, and the posterior lateral tooth is stained dark-brown. Uncommon. The Pacific Coast species is Cardita carpenteri Lamy (pi. 29r) which is V'z inch long and ranges from British Columbia to Lower California in shal- low to deep water. Its color is brownish gray with a purplish interior. Subgenus GJaiis Miihlf eld 1 8 1 1 Cardita dominguensis Orbigny Domingo Cardita North Carolina to southeastern Florida. % inch in length, ovate, inflated; beaks close together, pointing toward