White clam

Marine bivalve mollusc. The overall shape is trigonal ovate. The posterior margin is more pointed than the anterior; the anterior and ventral margins are rounded. Both the anterior and posterior dorsal margins are subconvex. The posterior half of the flank is slightly more inflated than the anterior. The valves are equal in size and shape (equivalve shell), and there is no gape when they are closed. Sculpture consists of rounded comarginal ribs. Ribs near the ventral margin may be split; splitting causes more ribs to be present at the posterior than the anterior. The lunule is lightly impressed, extends 3/4 of the anterior dorsal margin and is defined by a fine shallow groove. The commissural margin is slightly raised at the center of the lunule. The umbo is slightly anterior, and the beaks also point slightly to the anterior. The escutcheon is not well defined. The exterior color is light tan to light brown. The posterior dorsal margin may be a dark brown color. The interior is white with a purple or dark brown ray of pigment along the posterior dorsal margin.