672 DiY. 4. RABIA-TA— POLYPI. Class 4. 



the ovaries are attached ia the form of tangled threads. The intervals between the leaflets 

 have communications with the tentacula ; and it sliould scern that water enters by these, per- 

 vades the space between the leaflets, and ultimately escapes by small openings in the circum- 

 ference of the mouth ; at least, some of the Actiui;c eject water in this manner. 



Actinia. 



These have the body fleshy, often brilliantly coloured ; and the tentacula are arranged in several 



rows round the moutli, somewhat like the petals of a double flower, for which reason they have l)eeu 



r,(l.ir,/-r called " Sca-anemonies." They are very sensitive to light, and expand or close 



-■^^i4^1f//f ) /"' their tentacula according to the fineness of the day. When the tentacula are 



-'■'^ j^^ retracted, the aperture from which they proceed closes like the mouth of a purse, 



and the animal appears a simple fleshy tubercle, adhering to the rock. Their 

 reproductive powers are scarcely inferior to those of the Hydra. Amputated 

 parts are speedily re-produced ; and the numbers may be multiplied by simply 

 dividing the body ; though their usual mode of reproduction is by bringing forth 

 the young alive. These young pass from the ovary into the stomach, make their 

 escape by the moutli of the parent animal, and find localities for themselves. There are several dis- 

 tinctions among them, besides those of size and colour. All the Actinia; are voracious, and miscel- 

 laneous feeders. Small Fishes, Crustacea, and shelled MoUusca are, however, their usual food, and 

 they very speedily extract the contents, and eject the empty crusts and shells. 



Actinia proper, fix themselves by a broad and flat base. There are very many species, especially in tlio warmer 

 seas, where some of them are of largo size, and equal in brilliancy of ccilour to any flowers of the g-arden. The 

 species most common in Europe are, among; others, A. seni/is, which is three inches wide, with a leathery and 

 ruf^ged envelope of an orange colour, and two rows of tentacula of moderate length, marked with a ring of 

 rose-colour. It is found on the sands, into which it sinks if disturbed. A. eqitini.—Sk'ux soft, finely striated, of a 

 bright purple, often spotted with green ; body smaller than the last, but the tentacula longer and more numerous. 

 It abounds on the coasts of the Channel, and has a beautiful ai)pearance. A. pliimosa. — "White, more than four 

 inches wide, mouth in lobes beset with small tentacula, and with a row of larger ones within the lobes. A. effccta. 

 — Light brown with whitish streaks, smooth, lengthened, and often thickest at the upper part. Inhabits the Medi- 

 terranean, and usually fixes itself to shells. Those which have been enumerated are a mere specimen out of many 

 species, the distinctions of which are, however, often obscure. 



Thalannianlha and Discosoma of Ruppel, are Actinia', the first with branched, and the second with very short 

 tentacula. 



Zoaiithus, have the same texture, month, and tentacula as Actinia, anddift'er little in their general organization; 

 but they occur in groups adhering to a common base, which is sometimes broad and flat, and at other times a sort 

 of creeping stem. 



LUCERXARIA, — 



Resemble Actinia, but are of softer substance. They fi\ themselves by a slender peduncle to sea-weeds 

 and other bodies. The upper part expands like a parasol, and is surrounded by numerous tentacula, 

 arranged in bundles; and between these are eight cocca proceeding from the stomach, and containing 

 a red granulated matter. 



L. qnadricorna, has the edge in four forked branches, with two bundles of tentacula in each. L. auricula, has 

 the border octagonal, with a bunillc of tentacula in each division. 



THE SECOND ORDER OF THE POLYPI. 

 GELATIXOSI. 



These have no firm envelope, and no ligneous, fleshy, or horny axis within the body. They 

 are wholly gelatinous, more or less conical, and the simple cavity serves for a stomach. 



IIVDRA. 



These arc the sim|)lest of all animals in their organization, the whole of which consisis of a small, 

 gi'latnious horn, beset with lilaiucnis which serve as tentacula. Even the microscope linds nothing in 

 tlnir bodies but a transparent ])aienchyMui, cnntaining mere opaque granules ; still they can swim and 

 crawl, and even walk, by attaching the ends of the body alternately in a manner sindlar to Leeches and 

 geometrical Caterpillars. They distuib the water with their tentacida, and thus bring their prey within 



