Page:American Seashells (1954).djvu/480

398 2 to 3/4 inches in height, elongate, with 32 to 35 mostly smooth ribs. The ribs at the posterior end have small, tooth-like scales. Middle ribs com- pletely smooth and squarish. Externally light-cream with irregular patches of reddish brown. Interior china-white with the deepest part flushed with orange-buff. As a rule, the posterior margin is pale-yellow, merging into pale-purple at the extreme edge. A West Indian species which has been found on the most southerly keys. Tr achy car dium quadra genariurn Conrad Giant Pacific Cockle Plate 31a Santa Barbara to Lower California. 3 to 6 inches in size, commonly slightly higher than long, inflated, and with 41 to 44 strong, closely set, squarish, radial ribs which bear small, up- right, strong, triangular spines, especially at the anterior, posterior and ventral portions of the shell. Ribs on beaks smoothish. Exterior whitish tan, but commonly covered with a thin, opaque-brown periostracum. Interior dull- white. Moderately common from shore to 75 fathoms. Known locally as the Spiny Cockle. Genus Papyridea Swainson 1840 Papyridea soleniformis Bruguiere Spiny Paper Cockle Plate 39n North Carolina to south half of Florida and the West Indies. I to 1% inches in length, fairly fragile, moderately compressed, and gaping posteriorly where the margin of the valve is strongly denticulated by the ends of the dozen radial, finely spinose ribs. Exterior tawny with rose flecks or mottlings. Interior glossy, mottled with violet and white, rarely a solid pastel-orange. Moderately common from low tide to several fathoms. The name hiatus Meuschen used for this species in ]olmsonia is not valid (ruled non-binomial). A similar species, P. semisulcata Sowerby (Frilled Paper Cockle, pi. 32c) found from low water to 40 fathoms from southern Florida to the West Indies, is less than y-> inch in length, white, twice as fat, and with longer denticulations at the end of the 12 to 15 radial ribs. Uncommon, except off Miami where it is commonly dredged. Subjamily FRAGINAE Genus Trig07iwcardia Dall 1900 Trigojiiocardia media Linnc Atlantic Strawberry Cockle Plate 39m North Carolina to southeast Florida and the West Indies.