Page:American Seashells (1954).djvu/572

474 Subgenus Cochlodesma Couthouy 1839 Feriploma leanmn Conrad Nova Scotia to off North Carolina. Lea's Spoon Clam Plate 28V I to 1/4 inches in length, ovate, quite compressed, fairly fragile and white in color. Smoothish. The beaks located near the center of the dorsal edge of the valves have a natural, radial crease at the anterior end. Chondro- phore large, points ventrally and is reinforced anteriorly by a low, sturdy ridge. The muscle scar above the pallial sinus is commonly quite silvery. Periostracum thin and yellowish. Uncommon just offshore. This was put in a separate subgenus, Aperiplouia, by Habe in 1952.

Figure 97. Spoon and Dipper Clams, a, Periploum discus Stearns, i y^ inches (California); b, Ctispidaria ^lacialis Sars, i inch (Atlantic Coast); c and d, Verti- cordia ornata Orbigny, V^ inch (Atlantic Coast). Order SEPTIBRANCHIA Fmnily VERTICORDIIDAE Genus Verticordia Sowerby 1844 Subgenus Trigo7iidma Orbigny 1846 Verticordia oniata Orbigny Massachusetts to south half of Florida and the West Indies Ornate Verticord Figure 97c, d ^ inch in length, oval to round, compressed and with about a dozen strong, sharp, curved radial ribs on the anterior % of the valve. The ribs extend beyond the ventral margin to give a strongly crenulate margin. Exterior dull and cream-white; interior very silvery. Commonly dredged off our east coast from 5 to 200 fathoms, Verticordia (Haliris) fischeriana Dall is similar, but much fatter, % inch in length, and with about 28 small, finely beaded, radial ribs over the