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One of numerous small calcareous structures forming the skeleton of certain echinoderms, as the starfishes.

The region surrounding the anus, particularly of echinoderms.

The entire covering of an invertebrate animal, as echinoderm or coelenterate; the integument.

g ousel. -- Ring canal (Zoöl.), the circular water tube which surrounds the esophagus of echinoderms. -- Ring dotterel, or Ringed dotterel. (Zoöl.) See Dotterel, and Illust. of Pressiroster. -- Ring dropper, a sharper who pretends to have found a ring (dropped by himself), and tries to induce another to buy it as va…

Any one of numerous species of echinoderms of the order Echinoidea.

Any one of numerous species of echinoderms belonging to the class Asterioidea, in which the body is star-shaped and usually has five rays, though the number of rays varies from five to forty or more. The rays are often long, but are sometimes so short as to appear only as angles to the disklike body. Called also sea st…

An extensive group of echinoderms, comprising the starfishes and ophiurans.

le kingdom, as, in zoölogy, the Vertebrata, Tunicata, Mollusca, Articulata, Molluscoidea, Echinodermata, Coelentera, and the Protozoa; in botany, the Phanerogamia, and the Cryptogamia.

rod. See under Pump. -- Sucker tube (Zoöl.), one of the external ambulacral tubes of an echinoderm, -- usually terminated by a sucker and used for locomotion. Called also sucker foot. See Spatangoid.

The three anterior ambulacra of echinoderms, collectively.

ral. (Zoöl.) Same as Tubipore. -- Tube foot (Zoöl.), one of the ambulacral suckers of an echinoderm. -- Tube plate, or Tube sheet (Steam Boilers), a flue plate. See under Flue. -- Tube pouch (Mil.), a pouch containing priming tubes. -- Tube spinner (Zoöl.), any one of various species of spiders that construct tubel…

epression, in a palate, disk, or membrane; as, the umbo in the integument of the larvæ of echinoderms or in the tympanic membrane of the ear.

ous group of animals, formerly adopted by many zoölogists. It included the coelenterates, echinoderms, sponges, Bryozoa, Protozoa, etc.