ACTINIADJE. — The Actinice, or Sea-ane monies, so common on our coasts, known also by the name of " fleshy polypes," are evidently nearly allied to the preceding family, but in stead of secreting a calcareous polypary have their bodies entirely composed of a fleshy sub stance which, in appearance at least, is not very remote from muscular fibre. The ordinary Actini are of a conical forin, the base of the cone forming a strong sucker, whereby they attach themselves to foreign bodies, while, at the opposite extremity, which is truncated, is the opening of the mouth, surrounded with several rows of retractile tentacula, wherewith they seize their prey. They often elongate their bodies, and, remaining fixed by their base, they stretch from side to side as if to seek for food at a distance, and when thus stretched out they are very flexible and trans parent, but shrink on being irritated, and contract themselves so firmly, that it becomes almost impossible to distinguish them from the surface to which they are attached. Accord ,ing to some writers they can change their place by gliding upon their base; or detaching themselves entirely, they become swollen by the imbibition of water, and thus being rendered nearly of the same specific gravity as the sur rounding element are driven about in the sea until they choose to fix themselves again, when, by expelling the fluid from their bodies, they sink again to the bottom, and settling down 'become again fixed. It is even asserted that having detached their slickers they can turn themselves mouth downwards, and crawl by means of their tentacula, but our observations have failed to confirm these remarks.
The substance of the Actinia is entirely composed of transverse and perpendicular muscular fibres, which cross each other, the meshes of this interlacement being occupied by a multitude of granules, seemingly of a glandular nature, giving to the surface of the polype, which is covered with a gelatinous membrane, a tuberculated appearance. Ex ternally this fibrous membrane forms the parietes of the creature's body, expanding in feriorly into the basal disc, and superiorly, after forming a sphincter-like ring around the tentacula, is continued inwards to form the tentacula themselves (fig. 46, a), and then,
becoming more delicate in its texture, reflected into the interior of the body so as to form the stomachal cavity (b). Extending between the internal surface of the outer walls of the body and the exterior of the stomach are numerous longitudinal septa (c), evidently the homo logues of the vertical partitions of the Ale) o nide (fig. 31,f), and were these calcified by the deposition of' stony matter in their interior they would represent exactly the radiating septa in the cells of the polypary delineated infig,43, As in the preceding genera these mem branous septa support the organs of repro duction, which are constructed after the fol lowing manner.* The whole interior of the Actinia, between the stomach and the muscular parieties of the body, is divided by means of the septa into numerous longitudinal cavities, each of which communicates with the bases of two or three of the tentacula around the mouth t and encloses an ovary. Each ovary is composed of three or four cylindrical and coherent tubes of extreme delicacy, which, towards the base of the animal, are prolonged into a common canal, their opposite extremity- tapering to a point as the cogs become smaller, each ovary con taining about sixty eggs. The common tubes of two neighbouring ovaries unite into one as they issue from the longitudinal cavity, and this again joins the common canal of the next pair ; the resulting duct, which is thus common to four ovaries, opens into the stomach. The openings of these terminal tubes are arranged in a zig-zag direction, some opening lower down, others higher up.
Reaumur* believed that the young issued by a slit on each side of the body, situated beneath the fold of the muscular envelope that surrounds the bases of the tentacula, but the supposed openings are merely folds of' the skin, never perforate, and not always present. Nevertheless, as the tentacula are perforate at their extremities, and water is frequently forced out of the body through these open ings, it is possible that some ova may become detached and issue through these organs.