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Permanently attached; -- said of the gonophores of certain hydroids which never became detached.

One of the special defensive zooids of certain hydroids. They have the form of long, slender tentacles, and bear lasso cells.

zooids usually remain united by the stolons. Such stolons are often present in Anthozoa, Hydroidea, Bryozoa, and social ascidians. See Illust. under Scyphistoma.

Any one of numerous species of delicate, usually pink, calcareous hydroid corals of the genus Stylaster.

One of the transverse plants found in the calicles of certain corals and hydroids. Tabula rasa ( Etym: [L.], a smoothed tablet; hence, figuratively, the mind in its earliest state, before receiving impressions from without; -- a term used by Hobbes, Locke, and others, in maintaining a theory opposed to the doctrine of…

The chitinous cup which protects the hydranths of certain hydroids.

A division of hydroids comprising those which have the hydranths in thecæ and the gonophores in capsules. The campanularians and sertularians are examples. Called also Thecata. See Illust. under Hydroidea.

for international copyright." Charles Reade. -- Tooth coralline (Zoöl.), any sertularian hydroid. -- Tooth edge, the sensation excited in the teeth by grating sounds, and by the touch of certain substances, as keen acids. -- Tooth key, an instrument used to extract teeth by a motion resembling that of turning a key.…

A division of acalephs in which the development is direct from the eggs, without a hydroid stage. Some of the species are parasitic on other medusæ.

The nutritive zooids of a hydroid, collectively, as distinguished from the gonosome, or reproductive zooids.

A genus of hydroids having large, naked, flowerlike hydranths at the summits of long, slender, usually simple, stems. The gonophores are small, and form clusters at the bases of the outer tentacles.

Any hydroid belonging to the suborder Tubularida.

An extensive division of Hydroidea; the tubularians; -- called also Athecata, Gymnoblastea, and Tubulariæ.

Any hydroid which has tubular chitinous stems.

The circular membrane that partially incloses the space beneath the umbrella of hydroid medusæ.

One of the individual animals in a composite group, as of Anthozoa, Hydroidea, and Bryozoa; -- sometimes restricted to those individuals in which the mouth and digestive organs are not developed.

esemble plants in appearance, or mode of growth, as the corals, gorgonians, sea anemones, hydroids, bryozoans, sponges, etc., especially any of those that form compound colonies having a branched or treelike form, as many corals and hydroids.