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A mollusk having a shell consisting of two lateral plates or valves joined together by an elastic ligament at the hinge, which is usually strengthened by prominences called teeth. The shell is closed by the contraction of two transverse muscles attached to the inner surface, as in the clam, -- or by one, as in the oyst…

Having two valves, as the oyster and some seed pods; bivalve.

A shell or tube formed by an annelid, as a serpula.

That division of the Mollusca which includes the bivalve shells, like the clams and oysters; -- so called because they have no evident head. Formerly the group included the Tunicata, Brachiopoda, and sometimes the Bryozoa. See Mollusca.

Without a distinct head; -- a term applied to bivalve mollusks.

sed to abductor; as, the adductor of the eye, which turns the eye toward the nose. In the bivalve shells, the muscles which close the values of the shell are called adductor muscles. Verrill.

The exterior edge or border of a thing, as the border of a leaf, or the outline of a bivalve shell.

A genus of fresh-water bivalves, having to teeth at the hinge. [Written also Anodonta.]

A genus of bivalve shells, allied to the oyster, so called from their unequal valves, of which the lower is perforated for attachment.

A marine bivalve shell belonging to the genus Arca and its allies.

Destitute of a siphon or breathing tube; -- said of many bivalve shells. -- n.

A group of bivalve mollusks destitute of siphons, as the oyster; the asiphonate mollusks.

A genus of bivalve mollusks, common on the coasts of America and Europe.

r; auricled. (b) (Zoöl.) Having an angular projection on one or both sides, as in certain bivalve shells, the foot of some gastropods, etc. Auriculate leaf, one having small appended leaves or lobes on each side of its petiole or base.

A genus of marine bivalves, having a pearly interior, allied to the pearl oyster; -- so called from a supposed resemblance of the typical species to a bird.

, as in the Hemiptera. (d) The upper or projecting part of the shell, near the hinge of a bivalve. (e) The prolongation of certain univalve shells containing the canal.

A large bivalve shell of the East Indies (Hippopus maculatus), often used as an ornament.

The gills of some bivalves, as the oyster.

Having two adductor muscles, as a bivalve mollusk.

A glandular organ of bivalve mollusca, serving in part as a kidney.