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Southwest Florida Shells with Emphasis on Sanibel & Captiva

By José H. Leal

Family Cyrenidae

Polymesoda floridana

(Conrad, 1846)

Southern Marsh Clam

Shell size to 25 mm; shell trigonal, with rounded ventral and pointed posterior margins. Sculpture restricted to irregular growth lines. Color whitish with purple or pinkish-purple tints. Internally mostly white, but sometimes purple or white with purple margin. This is an estuaribe species that sometimes washes onto the passes around the barrier islands of Southwest Florida. Polymesoda maritima (d’Orbigny, 1853) is a synonym. Photos by Patricia A. Starkey.