tubular tentacula. The mouth is situated in the centre of the under surface. Now, if we imagine a Star-fish placed with the mouth upwards, its five rays fringed with long articulated tentacula, and fixed by the centre of the under or dorsal surface on a jointed stem, we shall have the essential character of a Crinoidean; and the animals of one recent genus of Stellerida are actually in this condition in the earlier stage of their existence: these are the Comatulæ, or feather-stars.*

It has been well remarked by Professor Forbes, that from the vast importance of the Crinoideæ in the economy of the ancient world, the history of the only crinoidal animal at present inhabiting the British seas, which at one time swarmed with those beautiful and wonderful creatures, must present many points of interest even to the general observer. The receptacle of the soft body of the Comatulæ, like that of the crinoideans, consists of a cup-shaped calcareous base, which sends off five arms, that quickly subdivide, and are beset on each side with rows of articulated pinna; on its convexity there are also numerous slender-jointed simple tentacula. The mouth is situated in the centre of the area, surrounded by the arms, and is capable of being elon

* The reader interested in this subject should peruse the elegant and charming volume on British Star-fishes and other Echinoderma, by Professor Forbes. 1 vol. 8vo. John Van Voorst. 1841.

gated into a proboscis. In the young state, the Comatulæ are attached by a jointed stem to other bodies, as shown in Lign. 69, fig. 1, which represents several of the natural size: fig. 1a. is an enlarged view of an individual, and closely resembles an expanded Crinoidean. The stem is composed of about eighteen joints, which are pentangular. After a few weeks the Feather-star becomes detached from its peduncle, and ranges the sea in freedom.*

Four fossil species of Comatula have been discovered in the Solenhofen slate; and it is not improbable that some of the numerous Crinoideans may be Stelleridæ in a young state.†

OPHIURA (serpent-like Star-fish) Lign. 73, fig.1.— The Star-fishes thus denominated have very long, slender, serpentine rays, without grooves and tentacula. These rays are extremely flexuous, and in some species armed with spines, by which they

* The researches of J. V. Thompson, Esq. brought to light these interesting facts in the Natural History of the Comatula; this eminent naturalist first discovered the pedunculated Comatulæ in the Cove of Cork.

+ When the discovery of Mr. Thompson was first made known to me, I suspected that the Marsupite might have been pedunculated when young; but as very small specimens are equally free from all traces of a peduncle as the adult, I was led to relinquish that opinion: still the collector should bear in mind the possibility of this having been the case, in searching for Crinoidean remains.

*

The

can entwine round, and seize their prey." structure of these rays is shown in the fragment from the Sussex chalk, Lign. 73, fig. 1.

Several

often in

species of this genus are found fossil, and the most perfect state, although, from the extreme fragility of some recent species, this could scarcely

Fig. 1a.-Part of the ray of an OPHIURA; nat. Preston. (Mr.

Walter Mantell.)

have been expected. One species has been found by our distinguished countryman, Professor Sedgwick, in the lowest Silurian deposits; and other

* See Prof. Forbes's Star-fishes, p. 22.

L

forms occur in all the succeeding fossiliferous formations, up to the most recent. The Lias, in the neighbourhood of Lyme Regis and Charmouth, has yielded several beautiful examples of Ophiura Egertoni, and other species. Professor Phillips

LIGN. 74.

FOSSIL STAR-FISH.

Lias. Wirtemberg.

ASTERIAS PRISCA. (Goldfuss.)

has figured a species (O. Milleri. Geol. York. Pl. XIII. fig. 20.) from the marlstone of Yorkshire; another (0. Prattii) occurs in the Oxford clay; and two or more species have been found in the Chalk, and London clay.

There is a recent genus of Star-fishes, called Euryale, which, in the multi-radiate character of the articulated dichotomous arms and their curious extremities, approaches very closely to the Crinoideæ, which it seems to connect with the Ophiuræ.

The Asterias are stellate in form; the rays are flat, and extend from the body, of which they are a prolongation, and have deep grooves bordered with marginal plates, extending to their extremities.

The Lias of Germany contains several species of Asterias (Lign. 74.). A large species occurs in the cornbrash of the oolite of this country; and our chalk has also yielded some beautiful examples.*

GONIASTER (Cushion-star). Lign. 73 and 75.— The Stelleridæ of this genus are of a pentagonal form, and bordered by marginal plates. The recent species are beset by spines; and, although I have observed no trace of such appendages in the fossils, I am induced to refer the species most common in the chalk to this genus, from the close analogy of their skeletons, both in form and structure, to the recent. The two species figured are well known, and were described by Mr. Parkinson (Org. Rem. Vol. III. Pl. I. figs. 1 and 3.). The detached ossicula of the

* A remarkably fine specimen of Asterias in Chalk, almost as perfect as if recent, has been discovered by Mrs. Smith, of Tunbridge Wells, and is preserved in that lady's choice collection.