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Rh Exterior orange-yellow; interior china-white. This is the largest species of recent cockles and is moderately common.

Genus Dinocardium Dall 1900

Dinocardiu77t robustum Solander Giant Atlantic Cockle Plate 32a

Virginia to north Florida, Texas and Mexico. 3 to 4 inches in size, ovate, inflated, with 32 to 36 rounded, radial, smoothish ribs. Externally straw-yellow with its posterior slope mahogany- red shading toward purple near the edge. Interior rose, with brownish posteriorly and with a white anterior margin. This is the large, common cockle washed ashore along the Carolina and Georgia strands. It is not found in southwest Florida.

When the Florida Canal project was begun in 1935, President F. D. Roosevelt was presented with a large silver platter on which was set a specimen of Di7iocardium, encased in gold and containing a portion of the first earth excavated as a result of the blast set off by the President. The canal was never completed.

Dinocardium robustwit vanhyningi Clench and L. C. Smith

Vanhyning's Cockle Plate 32b

Tampa Bay to Cape Sable, Florida.

3% to 5 inches in size, higher than long, with 32 to 36, smoothish, rounded, radial ribs. Externally straw-yellow with irregular patches and bands of mahogany-red to purplish brown. It is more elongate, glossier and more colorful than robustum, and is the common, large cockle on the west coast of Florida. They are popular souvenirs, being used for ash trays, melted-butter dishes, baking dishes and for holding pincushions.

Genus Serripes Gould 1841

There is only one species of this peculiar genus of cockles in North American waters. The hinge is narrow, the cardinal teeth weak, and the ligament is large. The radial ribs are very weak.

Serripes groenlandiczis Bruguiere Greenland Cockle

Plate 32d

Arctic Seas to Cape Cod, Massachusetts. Alaska to Puget Sound, Washington.

2 to 4 inches in length, moderately thin bur strong, inflated, almost