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430 Compare with lintea which lacks the dorsal crenulations. Formerly placed in the genus Tellina. Genus Quadrans Bertin 1878 Quadrans lintea Conrad Lintea Tellin Figure 86g North Carolina to both sides of Florida and the West Indies. % to I inch in length, moderately oval, slightly inflated, quite strong and all white in color. Posterior dorsal slope with 2 radial ridges in the right valve, i in the left. Concentric lamellae numerous, sharp and minutely raised. Left valve with 2 extremely weak, long laterals, but these are well- developed in the right valve. Dorsal line of the palhal sinus meets the pallial line not far from the anterior muscle scar. Posterior twist to the right is fairly pronounced. Commonly dredged off the Carolinas (9 to 16 fathoms), uncommonly found in a few feet of water on the west coast of Florida, Formerly placed in Tellina. Genus Tellidora H. and A. Adams 1856 Tellidora cristata Recluz White Crested Tellin Plate 30-0 North Carolina to west Florida and Texas. I to 1/4 inches in length, roughly ovate, compressed and all white. The left valve is very flat, the right valve slightly inflated. Dorsal margins of valves with large, saw-tooth crenulations. A bizarre clam found un- commonly in shallow water. Genus Macoma Leach 18 19 The Macomas are modified tellins which may be distinguished by (i) no lateral teeth; (2) usually dingy-white in color and of a chalky consistency; (3) there is a strong posterior twist; (4) the pallial sinus is larger in one valve than the other. Macoma calcarea Gmelin Chalky Aiacoma Figure 88f Greenland to Long Island, New York. Bering Sea to off Monterey, California. 1% to 2 inches in length. Oval-elongate, moderately compressed, but somewhat inflated at the larger, anterior half. Beaks % the way toward the narrowed, slightly twisted posterior end. Shell dull, chalky-white. Con- i