The Collaborative International Dictionary
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.) 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.
Pelecypoda \Pel`e*cyp"o*da\, n. pl. [NL., fr. Gr. ? a hatchet + -poda.] (Zo["o]l.) Same as Lamellibranchia.
WordNet
Usage examples of "pelecypoda".
Cal laid out his last shell and spoke into his typer: 'phylum Mollusca, class Pelecypoda, order Taxodonta, suborder Arcacea, family - forget it, I'll have to look it up.