422 POLYPI. VAGINATI. 



base and divided at their summit, polypiferous at their extre- 

 mity ; polypi not retractile, cylindrical, fasciculated, in the 

 form of an umbel, and clustered at the summit of the bran- 

 ches into globular heads, with eight large deeply pectinated 

 tentacula. 



X. wnbellata, Sav. Polypi deep blue, forming an umbellated head : 

 tentacula long, deeply pectinated. Red Sea. Lam. ii. 410. 



Gen. 5. ANTHELIA, Lam. 



Common body extended in a thin plate, or flattened over ma- 

 rine bodies ; polypi not retractile, projecting, straight and 

 crowded, occupying the surface of the common body ; eight 

 pectinated tentacula. 



A. glauca, Sav. Polypi green, subventricose below. Inhabits coasts 

 of the Red sea. Lam. ii. 408. 



ORDER III. POLYPI VAGINATI. 



Individual polypi tentaculated, constantly fixed in an inorganic 

 body which envelopes them, and forming in general com- 

 pound animals. 



The animals of this order, including the greater portion of the class, in general 

 grouped or agglomerated together, and communicating among themselves by their base, 

 participate in a common life. They are delicate, transparent, very contractile, and 

 are in general fixed to the inorganic body which they themselves form. This body is 

 increased in size as the polypi multiply by successive generations ; and the islands 

 raised in the middle of the ocean by these minute animals have no limits to their 

 breadth or length, and are only bounded in their height by the erection rising above 

 the level of the water which supplies them with food. 



These Polypi are contained in cells of the substance which they form in common, 

 and although they adhere to one another posteriorly or to the common mass, each 

 individual is almost always isolated in its particular cell. The basal mass is mem- 

 branous, horny or flexible, or in whole or part calcareous, and of stony hardness. 

 The animals have almost all tentacula disposed in a radiated form around their 

 mouth, either simple, dentated, or ciliated, and in various number. These tenta- 

 cula serve as a kind of arms to direct their food to the mouth. The ova are depo- 

 sited on the margin of their cells or dropped around, either naked or in particular 

 vesicles ; and thus the common body goes on to augment in size by the production 

 of successive generations. The cells of the polypi are short, long, or tubular, with 

 a regular or irregular orifice, and the interior walls, simple, &triated longitudinally, 

 or lamellated and stelliform. 



For a long period these polypiferous masses were conceived to be marine plants, 

 and they were accordingly arranged as a portion of the Vegetable Kingdom by 

 Tournefort. Peysonnel in 1727? however, discovered that the corals constituted the 

 habitation of minute animals : Trembley extended the discovery to the polypi of 

 fresh water ; Ellis, whose works still contain the standard information on many 

 of these tribes, discovered that analogous animals inhabited the Sertularia?, the Escha- 

 rae, Gorgonise, &c. ; and these bodies of uncertain derivation, as the Madrepores and 

 Millepores, were thus traced to be the abodes and the work, like the nest of the wasp 

 and the comb of the bee, of one of the most imperfect races of animals. 



As the form and consistence of the masses formed by the polypi, as well as their 

 own structure, is considerably varied, Lamarck has arranged the animals of this class 

 into seven sections, in the first two of which the polypiferous mass is composed of 



