POLY PE or Polyp, a class of the animal kingdom. The name is from the Greek vratiroti;, meaning many-footed, and usually comprises the animals of all zoophytes. Some Species, like the hydra, float about in the water separately, or are, like the ane mone, on rocks; but others secrete a habitation or basis, to which the term polypidom has been applied. These live in masses, formed by an aggregation of individuals. The polypary is the stem or central axis, and it is covered with a skin or membrane, partly gelatinous, partly calcareous. It is the coral of commerce. The more promin ent genera are actinic, astrea, caryophyllea, coral IMm hydra, isis, madrepora, meandrina, oculium, pociflopora, porita, sertularia, tubipora, and others. The polypes that make corals are chiefly Anthi pathos glaberrima, Madrepora corymbosa, M. pocil lifera, Gorgonia tuberculate, two species of Astrea, Leiopathes glaberrima, and L. Lamarckii. The Corallium nobilis, dredged in the Mediterranean, yields the red coral which, after pearls, is for ornamental jewellery the most precious product of the sea. Sicilian coral has fetched £10, 10s. the ounce. Tubipora musica has bright red cal careous tubes. It is used for ornament. The
brain coral is called Meandrina. The walls formed by polypi are always perpendicular. The madre pora abound near the islands of the Indian and Pacific Oceans, and cover the banks and reefs near the shores, particularly M. muricata, Linn. When still alive in the sea, the rough surface is seen dotted with red spots, which are the polype or coral insects, and a minute examination detects thousands of them, each inhabiting permanently a little cell of its own. Many of the polype or coral insects have a little parasol-shaped cover for the head ; the aims are furnished with eight claws, are long compared with the body, and are generally seen extended as if reaching for food. Some of the kinds of coral resemble gigantic plants with flowers and leaves. Some grow like a tree with leafless branches, and others spread out fan-like into broad flat surfaces. Those which build the coral reefs are not tidal animals, and require to be constantly submerged or washed by the breakers. Exposure to the sun's rays for a very short time invariably causes their destruction.—Darwin.