The animals belonging to this group, which may be characterised as stelliform or star-like, are very abundant in every sea, and in several geological formations. They constitute many families, among which may be noted the Milleporina of Ehrenberg, the polypidom of which Dr. Johnston describes as "calcareous, fixed, plant-like, branching or lobed, with cells scattered over the whole surface, distinct, sunk in little fosses, obscurely stellate, the lamellæ narrow and almost obsolete." (Johnston's Zoophytes, vol. i. p. 194.) In Turbinolia, the animal is simple, conical, striped, furrowed externally with larger and smaller ribs, the mouth surrounded by numerous tentacula, and solidified by a calcareous polypidom, which is free, conical, and also furrowed externally; attenuated at the base, but enlarged at the summit, and terminating in a shallow radiated lamellar cup or cell. Several species have been dredged off the coast of Cornwall, and the west coast of Scotland and Ireland.
T. melletiana is described as coral-white, wedge-shaped, somewhat compressed, with interspaces or ribs equidistant, smooth, and glossy. Above, the ribs turn over the edge, and are continued into the centre of the enlarged cup, forming its lamellæ. "That the zoophyte must have lived for some time after having become a movable thing, is proved," says Dr. Johnston, "by the ribs being continued beyond or round the point of attachment." The specimen here described was dredged alive, and Professor Forbes says of it that "it is a most interesting and beautiful species, the more so as it is certainly identical with Defrance's Turbinolia melletiana, found in both the crag formations."
Fig. 66. Caryophillia cyathus (Lamarck).
The Caryophilliæ (Lamarck), from καρύα, a nut, and ϕύλλου, a leaf, have the polypidom permanently fixed, simple, striated longitudinally, and the summit hollowed into a lamellated star-like cup; the animal, actinia-like, is provided with a simple, or double crown of tentacula, projecting from the surface of star-like, cylindrical, cone shaped cells. In C. cyathus (Lamarck) (Fig. 66), which inhabits the Mediterranean, the polyps are of a greyish colour, the tentacula streaked with black. The polypidom is erect and upright, sometimes cylindrical, and generally so firmly attached to the rock as to seem a part of it. The lamellæ are of three kinds: one large and prominent, between every pair of which there are three, sometimes five, smaller ones, the centre one being divided into two portions forming an inner series. The lamellæ are arched entire and striated on the sides, whence the margin appears somewhat crenelated. "It is found," says Mr. Couch, "of all sizes, from a mere speck to an inch in height. In a very young state, it is sometimes found parasitical on Alcyonium digitatum, on shells, and on the stalks of sea-weeds; but as these substances are very perishable, and offer no solid foundation, large specimens are never found on them. In its young state the animal is naked, and measures about the fifteenth of an inch in diameter, and about the thirty-second of an inch in height. In the earliest state in which I have seen the calcareous polypidom, there were four small rays, which were free or unconnected down to the base; in others I have noticed six primary rays, but in every case they were unconnected with each other. Other rays soon make their appearance between those first formed; they are mere calcareous specks at first, but afterwards increase in size. The first union of rays is observed as a small calcareous rim at the base of the polyp, which afterwards increases in height and diameter with the age of the animal."
The animals of this interesting polypidom are vividly described by Dr. Coldstream, in a communication to Dr. Johnston, as he observed them at Torquay:—
"When the soft parts are fully expanded," he says, "the appearance of the whole animal closely resembles an actinia. When shrunk, they are almost entirely hid amongst the radiating plates. They are found pendent," he adds, "from large boulders of sandstone, just at low-water mark. Sometimes they are dredged from the middle of the bay. Their colour varies considerably. I have seen the soft parts white, yellowish, orange-brown, reddish, and of a fine apple-green. The tentacula are usually paler."
The Caryophilliæ are sometimes dredged from great depths; Professor Travers dredged one in eighty fathoms, and Dr. Johnston remarks that the existence of an animal so vividly coloured at so great a depth is worthy of remark. "When taken," says the professor, "the animal was scarcely visible, being contracted; when expanded, the disk was conspicuously marked by two dentated circles of bright apple-green, the one marginal and outside the tentacula, the other at some distance from the transverse and linear mouth. In the dark, the animal gave out a few dull flashes of phosphorescent light."
In addition, we may mention the assertion of Mr. Swainson, that C. ramea, common in the Mediterranean, is occasionally found on the Cornish coast; but Dr. Johnston thinks it improbable that it could have escaped the attention of Mr. Couch and Mr. Peach, had it been so.
As belonging to this family, we present here illustrations of Flabellum pavoninum, Lesson (Fig. 67).