Animal and vegetable physiology, considered with reference to natural theology, by Peter Mark Roget .. . 50), and is the genus among thistribe that approaches the nearest in its cha-racter to the sponge, which it resembles in the * For the sake of greater distinctness I shall employ the termpolype to denote the single tube with its tentacula ; and shalldesignate by the Latin term polypus the entire animal mass com-posed of an aggregation of these polypes. Polypifera, the nameof the order, expresses animals bearing polypes. VOL. I. M 162 THE MECHANICAL FUNCTIONS. nature of its internal texture.
Animal and vegetable physiology, considered with reference to natural theology, by Peter Mark Roget .. . 50), and is the genus among thistribe that approaches the nearest in its cha-racter to the sponge, which it resembles in the * For the sake of greater distinctness I shall employ the termpolype to denote the single tube with its tentacula ; and shalldesignate by the Latin term polypus the entire animal mass com-posed of an aggregation of these polypes. Polypifera, the nameof the order, expresses animals bearing polypes. VOL. I. M 162 THE MECHANICAL FUNCTIONS. nature of its internal texture. Each of thepolypes with which its surface is studded haseight serrated tentacula. Fig. 57 represents oneof these polypes detached. Polypes may thus beunited in immense numbers in one mass, havingmutual organic connexion. In other cases theymay form smaller clusters, or be even totallyunconnected. Sometimes the detached polypesare still disposed to assemble in groups, as is thecase with the Zoanthus of Cuvier* (Fig. 58): atother times they are altogether isolated, as inthe Hydra viridis (Fig. 59).. Polypi form a very extensive order of zoo-phytes, abounding in every part of the ocean,but growing in greatest luxuriance in the The Hydra sociata of Gmelin; the Actinia sociata of Ellis. POLYPI. 163 warmer regions of the globe. Their flesh ex-hibits the same granular appearance as that ofthe sponge, but it is generally firmer, and oftenintermingled with masses of calcareous tentacula, which may be compared to arms,vary in number and in length in different spe-cies of polypi, and sometimes, instead of a singlerow, each of the mouths has two or more seriesof tentacula placed around it. They are formedof a prolongation of the soft substance of thepolypus, and are sometimes tubular; and theircavities are then continuous with that of thegeneral internal cavity into which the severalmouths open. Besides being flexible in everydirection, the tentacula are also capable of beingle
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