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An immensely long blackish seaweed of the Pacific (Macrocystis pyrifera), having numerous almond-shaped air vessels.

Of or pertaining to a division (Monocystidea) of Gregarinida, in which the body consists of one sac.

A division of Infusoria including the Noctiluca. See Noctiluca.

A lasso cell, or thread cell. See Lasso cell, under Lasso.

A genus of gigantic seaweeds.

An auditory cyst or vesicle; one of the simple auditory organs of many invertebrates, containing a fluid and otoliths; also, the embryonic vesicle from which the parts of the internal ear of vertebrates are developed.

The pouch in which incubation takes place in some Tunicata.

Inflammation of the tissues surrounding the bladder.

The cavity of a hydrophyllium.

A cyst or sac of a siphonophore, containing air, and serving as a float, as in Physalia.

One of the Polycystidea.

A division of Gregarinæ including those that have two or more internal divisions of the body.

A division of Radiolaria including numerous minute marine species. The skeleton is composed of silica, and is often very elegant in form and sculpture. Many have been found in the fossil state.

Pertaining to the Polycystina. -- n.

A defensive cell containing a minute rodlike structure which may be expelled. Such cells are found in certain Turbellaria.

A cavity in the primary nectocalyx of certain Siphonophora. See Illust. under Nectocalyx.

orms in the agamic reproduction of various trematodes and other parasitic worms. The sporocyst generally develops from an egg, but in its turn produces other larvæ by internal budding, or by the subdivision of a part or all of its contents into a number of minute germs. See Redia.

One of the auditory organs of certain medusæ; -- called also auditory tentacle.

A lasso cell.

The urinary bladder.