pelecypoda

from The Century Dictionary.

• The bivalve mollusks; the conchiferous or acephalous bivalves, usually called Lamellibranchiata, Acephala, or Conchifera: so named as a class from the shape of the foot in some forms. Goldfuss.

from the GNU version of the Collaborative International Dictionary of English.

• noun plural (Zoöl.) Same as lamellibranchia.