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A digestive gland in Crustacea, Mollusca, etc., usually called the liver, but different from the liver of vertebrates.

Characterized by a current which flows inward; as, the incurrent orifice of lamellibranch Mollusca.

A class of Mollusca including all those that have bivalve shells, as the clams, oysters, mussels, etc.

An extensive group of Invertebrata, including the Mollusca, Brachiopoda, and Bryozoa. Called also Malacozoaria.

f Invertebrata which includes the classes Brachiopoda and Bryozoa; -- called also Anthoid Mollusca.

Molluscan.

One of the Mollusca. [Written also mollusc.]

One of the cells which secrete the chitinous teeth of Mollusca.

A division of gastropod Mollusca, in which the breathing organs are usually situated behind the heart. It includes the tectibranchs and nudibranchs.

Having the pulmonary sac situated posteriorly; -- said of certain air-breathing Mollusca.

The olfactory organ of some Mollusca. It is connected with the organ of respiration.

A genus of bivalve Mollusca which includes the true oysters.

A division of gastropod Mollusca, including the chitons. The back is covered by eight shelly plates. Called also Polyplacophora. See Illust. under Chiton, and Isopleura.

A class of Mollusca in which the anterior lobes of the foot are developed in the form of broad, thin, winglike organs, with which they swim at near the surface of the sea.

A class of marine cephalate Mollusca having a tubular shell open at both ends, a pointed or spadelike foot for burrowing, and many long, slender, prehensile oral tentacles. It includes Dentalium, or the tooth shells, and other similar shells. Called also Prosopocephala, and Solenoconcha.

An order of gastropod Mollusca having a heart with two auricles and one ventricle. The shell may be either spiral or shieldlike.

An order of lowly organized Mollusca belonging to the Isopleura. A narrow groove takes the place of the foot of other gastropods.

Of or pertaining to the mouth and the stomach; as, the stomatogastric ganglion of certain Mollusca.

An extensive division of gastropod Mollusca in which the loop or visceral nerves is twisted, and the sexes separate. It is nearly to equivalent to Prosobranchiata.

ons of either the animal, or vegetable kingdom, as, in zoölogy, the Vertebrata, Tunicata, Mollusca, Articulata, Molluscoidea, Echinodermata, Coelentera, and the Protozoa; in botany, the Phanerogamia, and the Cryptogamia.