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170 American Seashells
Crucibulum spinosum Sowerby Spiny Cup-and-saucer
Southern California to Chili.
Figure yi
% 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
Nova Scotia to South Carolina (and Florida?).
Plate 2ir
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
Bering Sea to Panama.
Plate 20k
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.