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An order of marine Bryozoa, having a bilobed lophophore and an axial cord. The genus Rhabdopleura is the type. Called also Podostomata. See Rhabdopleura.

Same as Pulmonibranchiata, -ate.

Same as Pulmonata.

Same as Pulmonate.

A division of opisthobranchiate mollusks having the branchiæ in a wreath or group around the anal opening, as in the genus Doris.

Same as Scutibranchiata.

One of the Scutibranchiata.

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

Having the gills protected by a shieldlike shell; of or pertaining to the Scutibranchiata. -- n.

A tribe of gastropods having the mantle border, on one or both sides, prolonged in the form of a spout through which water enters the gill cavity. The shell itself is not always siphonostomatous in this group.

a siphon, or siphons, to convey water to the gills; belonging or pertaining to the Siphonobranchiata. -- n.

Situated above the branchiæ; -- applied especially to the upper division of the gill cavity of bivalve mollusks.

Same as Tectibranchiata.

An order, or suborder, of gastropod Mollusca in which the gills are usually situated on one side of the back, and protected by a fold of the mantle. When there is a shell, it is usually thin and delicate and often rudimentary. The aplysias and the bubble shells are examples.

Having the gills covered by the mantle; of or pertaining to the Tectibranchiata. -- n.

An order of Cephalopoda having four gills. Among living species it includes only the pearly nautilus. Numerous genera and species are found in the fossil state, such as Ammonites, Baculites, Orthoceras, etc.

Of or pertaining to the Tetrabranchiata. -- n.

Having the gills situated upon the neck; -- said of certain mollusks.

One of the gill-like breathing organs of certain aquatic insect larvæ. They contain tracheal tubes somewhat similar to those of other insects.

The gill of a crustacean in which the branchial filaments are slender and cylindrical, as in the crawfishes.