Page:American Seashells (1954).djvu/219

Rh I % inches in diameter, Vs as high, obhquely ovate, fairly thin, and with a small, hooked-over apex. Shell w^hite, covered by a soft, fuzzy, light-brown periostracum. Interior glossy-white. A rather rare species found in 20 to 30 fathoms attached to Pecten diegensis.

Family CALYPTRAEIDAE Genus Calyptraea Lamarck 1799 Calyptraea centralis Conrad Circular Cup-and-saucer Plate 21-0

North Carolina to Texas and the West Indies.

/4 to % inch in diameter, cap-shaped, with a circular base, and pure white in color. Apex central, small, minutely coiled and glossy-white. The shelly cup is attached to the inside of the shell and is flattish, arises near the center of the shell and flares out to the edge. Its free side is thickened into a columella-like, rounded edge. Commonly dredged in shallow water, espe- cially off southeast Florida. Formerly known as C. candeana Orbigny.

Calyptraea fastigiata Gould Pacific Chinese Hat Plate 20I

Alaska to southern California.

Ys to I inch in diameter, about H to % as high; the outline of the base of the shell is perfectly circular, and the apex is at the center of the shell. Interior glossy-white with the sinuate edge of the internal cup arising at the apex of the shell as a thickened, twisted columella and ending in fragile at- tachment near the edge of the shell. Young forms (C. contorta Cpr.) are relatively higher-spired. Exterior chalky-white with a thin, brownish perios- tracum. Dredged moderately commonly from lo to 75 fathoms.

Genus Crucibulum Schumacher 18 17 Crucibulum auricula Gmelin West Indian Cup-and-saucer Plate 2 IS

West Florida to the Lower Keys and West Indies.

I inch in diameter, similar to C. striatum, but the edges of the inner cup are entirely free. The edges of the main shell are crenulated, the external ribs are coarser, and the interior is sometimes pinkish. The outer surface may show coarse diagonal ribs if the specimen has lived attached to a scallop or other ribbed mollusk. Uncommonly dredged in shallow water and occasion- ally washed ashore.