Page:American Seashells (1954).djvu/532

434 Aiacoma incongnm von Martens (fig. 88b) (Alaska to Washington) is similar, but more oval, with a more pointed slope at the beaks, a straighter posterior dorsal edge. Its upper pallial sinus line, after nearly reaching the anterior muscle scar, turns downward and then runs anteriorly before con- necting with the paUial sinus. Common in Alaska. Genus Apoly metis Salisbury 1929 Apolymetis intastriata Say Atlantic Grooved Macoma Plate 32y South half of Florida and the Caribbean. 2 to 3 inches in length, elliptical, fairly thin but strong and all white in color. The shell is strongly twisted. At the posterior end, the right valve bears a strong, radial rib, while on the left valve there is a fairly strong, radial groove. Pallial sinus very large. Living specimens are not commonly col- lected, although shells are commonly washed ashore. Apolymetis biajigiilata Carpenter Pacific Grooved Macoma Santa Barbara, California, to Ensenada, Mexico. 2 to 3 V2 inches in length, oval, moderately compressed, strong, and dull grayish white in color. Interior glossy-white with the central portion blushed with pastel-peach. Left valve with a shallow, radial groove near the posterior end. Right valve with a corresponding ridge at the end of which the margin of the shell is shallowly notched. Alias A. alta Conrad. Common. Family SEMELIDAE Genus Semele Schumacher 18 17 Resilium supported in a horizontal, chondrophore-like depression which is internal and parallel with the hinge line. 2 cardinal teeth in each valve. Right valve with 2 distinct lateral teeth, but practically absent in the left valve. The ligament is external. Semele proficua Pulteney White Atlantic Semele Plate 40g North Carolina to south half of Florida and the West Indies. /4 to 1/4 inches in length, almost round, beaks almost central. Lunule small and pushed in. Fine concentric lines and microscopic radial striations. Externally whitish to yellowish white. Interior glossy, commonly yellowish, rarely speckled a little with purple or pink. Moderately common in shallow water. The color form radiata Say, has a few indistinct radial rays of pink (pl.400.