The Basket Clams - Family Corbulidae

THE BASKET CLAMS - FAMILY CORBULIDAE. Genus CORBULA, Brug.

Shell

small, thick, gaping in front, valves unequal, hinge formed by a recurved tooth fitting into a socket; animal unsym metrical; mantle closed, except for the pedal aperture in front, with toothed edges; siphons united, short, fringed. An interesting group of small bivalves living in sand or mud.

The Contracted Basket Clam (C. contracta, Say) has its unequal swollen valves presenting an almost circular outline when seen end on, and drawn out to a truncated point at the posterior end. The surface bears regular small concentric ridges. Length, inch.

Habitat.— Cape Cod to West Indies.

C. nasuta, Say, is more nearly equivalve, pointed more sharply at the posterior end, but more nearly circular in the outline of each valve. Ridges fine and close. Length, inch.

Habitat.— Cape Hatteras to Haiti.

The Yellow Basket Clam (C. luteola, Cpr.) is shaped like the familiar little Donax. Its yellow shell shows faint lines of growth; the edges are thickened and turned inward. Length, inch.

Habitat.— Southern California.

The British Basket Clam (C. gibba, Olivi.) is swollen so out of symmetry that the right valve contains the body, and the left is like an operculum. The extended shell forms a protective roof for the siphons. The foot is tongue-like.

Cryptomya Californica,

Conn, has thin, whitish, elliptical unequal shell, faintly checked with crossing striations, gaping behind; a peg and socket hinge; internal ligaments; the short siphons not covered with tough skin. Length, I inch.

Habitat.— California.

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