Page:American Seashells (1954).djvu/481

Rh I to 2 inches in size, squarish in outline, thick, inflated, with 33 to 36 strong radial ribs which are covered with close-set, chevron-shaped plates. External color whitish with mottlings of reddish brown. Interior usually white, or may be flushed with orange, rose-brown or purple. The posterior slope is pushed in somewhat and is slightly concave. A relatively common species found in shallow to moderately deep water. The Western Strawberry Cockle, T. biangiilata Sowerby, is the Cali- fornian counterpart of the above species. It is iVi inches in length, with about 30 strong ribs; exterior yellowish white, interior reddish purple. Moderately common. Subjavnly PROTOCARDIINAE Genus Nemocardium Meek 1876 Nemocardhnn centifilomin Carpenter Hundred-lined Cockle Alaska to Lower California. % to % inch in length, almost circular; posterior third of shell with cancellate sculpturing and separated from the finely ribbed anterior two thirds of the shell by a single raised rib. Edge minutely serrate. Exterior with gray, greenish gray or brownish gray, thin, fuzzy periostracum. In- terior dull- white. Fairly common. Genus Microcardiwn Thiele 1934 Microcardiwn peramabile Dall Eastern Micro-cockle Rhode Island to southeast Florida and the West Indies. % to % inch in length, thin, inflated, subquadrate, white, but may be mottled tan on the anterior slope. Sculpture prominent on the posterior third of the valve. It consists of about 90 closely packed, radial ribs (spinose posteriorly) which are crossed by minute concentric threads. The anterior two thirds is separated from the rest of the shell by a single, crested, spinose, radial rib. Very commonly dredged off eastern Florida. Microcardium tinctu?n Dall, found with the above species, is % inch in length, stained with rose-red and has more than 150 minute, radial ribs. Uncommon. Siibjainily LAEVICARDIINAE Genus Laevicardimn Swainson 1840 Laevicardium laevigatum Linne Common Egg Cockle Plate 39k North Carolina to both sides of Florida and the West Indies.