noun. One of the leading divisions of invertebrated animals; an extensive series of invertebrates whose bodies are soft, without any jointed legs, and commonly covered with a hard shell in one, two, or more pieces, and whose principal parts are neither segmented into a series of longitudinal rings, as in insects, crustaceans, and worms, nor radiately arranged, as in echinoderms; the mollusks, as the univalve or bivalve shell-fish of ordinary language.

proper noun plural. One of the grand divisions of the animal kingdom, a phylum including the classes Cephalopoda, Gastropoda, Pteropoda, Scaphopoda, and Pelecyopoda (syn. Bivalvia, formerly called Lamellibranchiata, or Conchifera). These animals have an unsegmented bilateral body, with most of the organs and parts paired, but not repeated longitudinally. Most of them develop a mantle, which incloses either a branchial or a pulmonary cavity. They are generally more or less covered and protected by a calcareous shell, which may be univalve, bivalve, or multivalve.

noun. gastropods; bivalves; cephalopods; chitons

"In the animal kingdom, the mollusca are the rasorial type, which, however, only shews itself there in their soft and sluggish character, and their being very generally edible."

phylum  

Lepidoptera  alga  arthropoda  bivalve  brooklet  

Mollusca