La·mel·li·bran·chi·a La·mel·li·bran·chi·a·ta n. pl. Zool. An earlier name for the class of Mollusca including all those that have bivalve shells, as the clams, oysters, mussels, etc., now called Pelecypoda or Bivalvia.
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.
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