Cockles

Habitat.-Japan to Alaska, southward to San Diego, Cal.

C. Californiense, Desh., has very close, flat ribs, often so low that the furrows are but scratches on the surface. It ranges with the last species as far as Monterey. Several varieties occur farther north.

C. quadrigenarium, Conr., is the western counterpart of C. magnum. Its forty or more toothed ribs cover a capacious pair of valves. In early youth the shell is smooth. Colour dingy, with yellow teeth and lips. It is taken from deep water. Diameter, 4 to 5 inches.

Habitat.-Pacific coast.

The Great Cockle (C. elatum, Sby.) has a very ventricose strong shell with yellow shining surface scored with deep grooves. It is the largest of American cockles, attaining six inches in diameter.

Habitat.-Panama to Santa Barbara, Cal.

The Ribbed Cockle (C. costatum, Linn.) has scarcely a distinctive name in a genus where all shells are ribbed. This species shows an elegance of sculpture that is unexampled in the forms described above. The deep, grooved and ridged sulci are few, because they are so large; the sharp-edged ridges, similarly chiselled with secondary ridges, are few and well apart. The nine ribs converge in elevated beaks that meet over a straight hinge line. The shells are thin, almost translucent, the white surface bears a brown marginal band, and the sulci are brown. Length, 3 or 4 inches.

Habitat.-East coast of Africa.

Genus LIOCARDIUM, Swains.

Shell oval, elongated, oblique, inequilateral; surface smooth.

L. serratum, Linn., has only fine, concentric growth lines to roughen its smooth surface. The valves are deep, round saucers, thin as our grandmother's tea set, the white exterior tinged creamy by the rich yellow that lines it. Children playing at housekeeping on Florida beaches call these indispensable little shells, "buttercups." Diameter, 2 inches.

Habitat.-Cape Hatteras southward.

The Egg Shell Cockle (L. substriatum, Conr.) thin, showing only faint remnants of ribs, is splotched, especially within, with reddish brown, as certain birds' eggs are. The valves are circular with elevated beaks. Diameter, 1 to 1 1/2 inches.

Habitat.--California.

Genus SERRIPES, Beck.

Shell subcordate, compressed, thin, almost equilateral; surface with obsolete, radiating ribs; beaks prominent; cardinal hinge teeth wanting.

S. Groenlandicus, Chemn., has the generic characters. It is invested with a drab or olive epidermis. Length, 2 or 3 inches.

Habitat.-Maine northward, Alaska, Puget Sound.