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Rh adjacent and internal in a triangular resilifer; left valve with 2 diverging cardi- nal teeth; right valve with 3, of which the posterior one is more or less obso- lete. 3 laterals in each valve. Crassatella Lamarck is fossil and not this genus. Crassatellites Krueger is believed to be invalid. Eucrassatella speciosa h. Adams 1852 Gibb's Clam Plate 30Z North Carolina to both sides of Florida and the West Indies. 1V2 to 2/0 inches in length, % as high, heavy, beaks at the center, and the shell somewhat diamond-shaped. Concentric sculpture of neat, rather heavy, closely packed ridges (about 15 per half inch). Lunule and escutcheon sunken, lanceolate in shape and about the same size as each other. Exterior with a thin, persistent, nut-brown periostracum. Interior glossy ivory with either a tan or pink blush. Moderately common just offshore in sand. C. floridana Dall is the same, being based on a young specimen. E. gibbesi Tuomey and Holmes 1856 is a synonym. Genus CrassineUa Guppy 1874 Shell small, compressed, subtriangular, and slightly inequivalve. 2 cardi- nals in each valve, i anterior lateral in the right valve, i posterior lateral in the left valve. CrassineUa lunulata Conrad Lunate CrassineUa Figure 28k North Carolina to both sides of Florida and the West Indies. /4 to H inch in length, as high, quite compressed, solid, with the tiny, closely pressed-together beaks at the middle or slightly toward the anterior end. Dorsal margins straight and about 90 degrees to each other, the anterior margin slightly longer and with a der sunken area. The valves are pecu- liarly askew, so that the posterior dorsal margin of the left valve is more obvious than that of the right valve. Concentric sculpture of coarse but well- developed ribs (about 15 to 17 plainly visible). Color whitish or pinkish, interior commonly brown. Sometimes faintly rayed. A common shell from beach to 60 fathoms. CrassineUa mactracea Lindsley Lindsley's CrassineUa Plate 30b Massachusetts Bay to Long Island, New York. Almost identical with lunulata from more southern waters, but more obese, with a more oval lunule, and generally with a chalky texture to the