Page:American Seashells (1954).djvu/220

Crucibulum spinosum Sowerby Spiny Cup-and-saucer Figure yi Southern California to Chili. % to I inch in diameter, variable in height ( % to % as high), and usually with an almost circular base. Exterior with a smoothish apical area, the re- mainder of the shell with radial rows of small prickles or sometimes erect, tubular spines. Interior glossy, chestnut-brown, sometimes with light radial rays, and with a delicate white cup attached by one side. A very common species from low water to 15 fathoms. Albino shells are sometimes found. Subgenus Dispotaea Say 1826 Crucibulum striatum Say Striate Cup-and-saucer Plate 2ir Nova Scotia to South Carolina (and Florida?). I inch in diameter, cap-shaped, base round, edge smoothish and the slightly twisted apex near the center of the shell. Interior of shell with a small, shelly cup, of which only 73 is free from attachment to the main shell. Apex wax color and smooth; remainder of exterior with small, wavy, radial cords. Interior glossy, yellow-white or tinted with light orange-brown. Commonly dredged in shallow water. Genus Crepipatella Lesson 1830 Crepipatella lingiilata Gould Pacific Half-slipper Shell Plate 20k Bering Sea to Panama. H to % inch in diameter, thin, almost circular, low and with the apex near the edge of the shell. Characterized by its tannish to mauve-white, glossy interior which has a shallow deck which is attached to the main part of the shell only along one side. The middle of the deck often has a weakly raised ridge. Exterior wrinkled and brownish. A very common species found on rocks and on the shells of living gastropods. Genus Crepidula Lamarck 1799 Crepidula fornicata Linne Common Atlantic Slipper-shell Plate 2im Canada to Florida and to Texas. % to 2 inches in size. Shelly deck extending over the posterior half on the inside of the shell. The deck is usually concave and white to buff. Its edge is strongly sinuate or waved in two places. Exterior dirty-white to tan, sometimes with brownish blotches and rarely with long color lines.