rarely be obtained, except through the quarrymen who have been instructed what objects to preserve. The first specimen of this kind ever noticed, was discovered in a mass of chalk which I was breaking up in search of fungiform flints; when, to my great delight, I found the fossil, Lign. 61, fig. 3, which at once established the connexion between the flat chalk specimens, Lign. 61, figs. 1, 2, and the flints figured Lign. 60, figs. 2, 3, 6, 7, 8. Upon showing this fossil to the quarrymen, and exciting their attention by suitable rewards, I obtained the illustrative series now in the British Museum. Much light would probably be thrown on the nature of the organization of other zoophytes of the chalk that have undergone this mode of petrifaction, if due care were taken in their collection, and they were examined before extracted from the stone in which they are imbedded. Loose, delicate specimens, whether from the chalk or tertiary strata, should be affixed, with strong gum-water, to cards, or on pieces of thin board, covered with suitable coloured paper.

may

The Shanklin-sand Spongites, Siphoniæ, &c. often be extracted from the rock tolerably perfect, by a well-directed blow of the hammer; but delicate specimens should be left attached to a block, and the surrounding stone be carefully chiselled away, so as to expose the most essential characters.

The Faringdon zoophytes are, for the most part,

encrusted by an aggregation of minute polyparia, shells, and detritus, which may be partially removed by washing with a stiff brush, and their cavities cleared with a stout penknife, removing the extraneous matter by chipping, not by scraping, or the surface will be injured. In this manner the beautiful specimens figured Wond. pp. 560, 561, were developed.

The Corals in the hard limestones can seldom be chiselled out to advantage; for the most part, polished sections are the best specimens for the display of the form and structure of the originals.

The silicified zoophytes of the West Indies, and those from Ava, and the Sub-Himalayas, form beautiful subjects for the microscope; and chips, or sections, should be prepared in the manner recommended for fossil-wood in the same state of mineralization.

LOCALITIES. The gravels and sands are the most favourable sites for obtaining the Tertiary zoophytes. Mr. Bowerbank has very recently discovered a new species of Astrea (A. Websteri) at Bracklesham Bay.

The stone quarries, in that division of the Oolite called Coral-Rag (as in the north-west of Berkshire, Oxfordshire, Gloucestershire, &c.), afford the usual corals of the Oolite.

The Oolite near Bath contains many species, and large masses wholly composed of a minute coral

(Eunomia radiata, Ly. II. p. 43.), are abundant. The Shanklin Sand gravel-pits, near Faringdon, in Berkshire (see Wond. p. 560.), abound, as already mentioned, in many kinds of sponges, and other Amorphozoa; and the quarries of oolitic limestone in the vicinity of that town, yield the usual corals of the formation, in profusion. I know of no locality so rich in these remains.

At Steeple Ashton, in Wiltshire, numerous Caryophylliæ, and other oolitic corals may be obtained. The silicified Astrea, of Tisbury, in the same county, have been particularly described.

Clifton, near Bristol, Torquay and Babbicombe, on the Devonshire coast, are celebrated for their coralline marbles and pebbles. And many of the Derbyshire limestones are equally prolific in similar remains.

Dudley, Wenlock, and Ludlow, are well known, as affording innumerable examples of fossil zoophytes, in great perfection.

I content myself with this brief notice, as the localities of the principal kinds of British zoophytes, have been incidentally mentioned in the course of our previous review.

CHAPTER IX.

FOSSIL ECHINODERMA; COMPRISING THE CRINOIDEÆ, OR LILYLIKE ANIMALS; STELLERIDÆ, OR STAR-FISHES; ECHINIDÆ, OR SEA-URCHINS.

THE fossil remains of the Echinoderma (spinyskin animals) are found among the earliest traces of animal existence hitherto discovered; for numerous species of the Crinoideæ, and one genus of the Stellerida, occur in the Silurian deposits.

The animals of this group present the radiated character very decidedly, for their parts are arranged around one common centre; the star-fish and sea-urchin of our coasts are familiar examples of this type of organization. Their external integument or skin is, in most examples, protected by spines (hence the name of the order), and in general perforated by minute foramina for the admission of sea-water, or the protrusion and retraction of minute tubes or hollow tentacula, which constitute their common organs of adhesion and locomotion. The two first families have their skeletons formed

THE MEDALS OF CREATION.

CHAP. IX.

of numerous ossicula, or little calcareous bones; the last, of crustaceous brittle plates. These durable parts of the animal fabric occur in immense quantities in the sedimentary deposits; and in many parts of England, and of northern Europe and America, entire mountain-chains are chiefly composed of the bones and detritus of Crinoidea, belonging to numerous extinct species and genera.

Diversified in figure as are the animals arranged in this section, they are naturally related by their organization. The Crinoides may be regarded as star-fishes fixed to one spot by a jointed stem; the Star-fishes as free Crinoidea; and the Echinida as star-fishes with the rays coalesced and united together into a globular or spherical case.

FOSSIL CRINOIDEA.—The fossil remains of the Crinoideæ, have long since received the name of Stone-lilies, from the fancied resemblance of the body of the animal when in a state of repose to a closed lily or tulip; but this appellation is generally restricted to those which have cylindrical or elliptical stems; the term Pentacrinite, being applied to those whose support is made

ossicula.

up

of angular

One living species only is known, the Pentacrinus Caput-Medusa, an inhabitant of the Caribbean Sea (Wond. p. 580.). This animal has a long jointed stem, which is fixed at its base by radicle processes, and supports a cup-like receptacle, formed of a series of calcareous plates closely