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acephala |
2 definitions found From Webster's Revised Unabridged Dictionary (1913) [web1913]: Lamellibranchia \La*mel`li*bran"chi*a\, Lamellibranchiata \La*mel`li*bran`chi*a"ta\, n. pl [NL. See {lamella}, and {Branchia}, {Branchiate}.] (Zo["o]l.) A class of Mollusca including all those that have bivalve shells, as the clams, oysters, mussels, etc Note: They usually have two (rarely but one) flat, lamelliform gills on each side of the body. They have an imperfectly developed head, concealed within the shell, whence they are called {{Acephala}}. Called also {Conchifera}, and {Pelecypoda}. See {Bivalve}. From Webster's Revised Unabridged Dictionary (1913) [web1913]: Acephala \A*ceph"a*la\, n. pl [NL., fr Gr ?, adj neut. pl., headless. See {Acephal}.] (Zo["o]l.) 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}.