The Green Sand of Wiltshire abounds in small species of Cidaris and Nucleolites; and Chute Farm, near Heytesbury, is a celebrated locality for these remains.

The large sinuated Clypeus is found in great perfection at Malton, and also in the Oolite, near Cheltenham.

The Chalk Echinites are to be met with in most localities of that formation; but certain species prevail in each division. The smooth Spatangi abound in the Galt and Chalk-marl, and the Galerites vulgaris, Ananchytes ovatus, and Spatangus cor-anguinum, in the upper White Chalk.

ON COLLECTING AND DEVELOPING FOSSIL ECHINODERMA.—In our previous remarks on the radiated animals comprised in this survey, we have pointed out those characters which are the most important, and which it should be the especial object of the student to discover in a fossil state. Thus, in searching for fossil Crinoideans, the receptacle or body should be the principal object; and if only detached plates can be extracted from the rock, their natural position should be carefully noted, and the specimens glued to a card or board, in that order; and some of the ossicula of the column, and of the arms, or tentacula, be placed with them.

Mr. Miller dissected specimens of every genus, and has figured the separate plates or bones that enter into the composition of the pelvis, column, and arms. Traces of the arms, and their subdivisions, must be sought for, and if any be discovered, they should be removed with the blocks of stone to which they are attached, and the stone afterwards reduced in size by a mason's saw, and not by blows of a hammer, which would displace the delicate ossicula.

When imbedded in Lias shale, or other fragile material, a thick slab should be removed, for greater safety in conveyance; this, when reduced to a convenient size and thinness, should be placed in a tray with plaster of Paris, or glued to a piece of thin, well-seasoned mahogany, or oak. The specimens of the Pear Encrinite of Bradford (by Mr. Pearce), and of the Pentacrinites from Lyme Regis (by Miss Mary Anning), in the British Museum, were prepared in this manner.

The crinoideal remains in the Chalk belong but to few genera; they merely require the usual manipulation of cretaceous fossils; but the collector should remember that the ossicula and plates of the pelvis (as for instance in the Marsupite), are but slightly adherent to each other, and the chalk must not be wholly removed, or they will become detached. The receptacle of the Apiocrinite of the chalk is rarely found with more than a few joints of the column attached; and I believe no vestige of the arms has been observed: these parts

are therefore desiderata, and should be sought for diligently; the radicles of this crinoidean are long, articulated, and branching, and, without due caution, may be mistaken for the arms, or for another species. The first remark will also apply to the Marsupite; any specimens with but a few ossicula of the arms are very precious. I may observe that there is yet much to learn as to the number of species and genera, and the peculiar characters of the Crinoides of the chalk, and that any addition to our knowledge on this subject will be valuable. The Stelleride are so simple in form and structure, that it is unnecessary to offer any suggestions for their development; the more perfect they can be obtained the better: of course they must not be removed from the stone. Among the detached calcareous echinodermal ossicula diffused through the chalk, the student will remember that the large coral-like tubercle of the Star-fish may often be presented to his notice. It may easily be mistaken for an encrinital body, or for a coral, but an accurate inspection will show that it is not composed of anchylosed plates, like the receptacle of an Apiocrinite, but has surfaces for attachment to the surrounding ossicula; while the extremities, which in a crinoideal column would present radiated surfaces, are rounded and entire.

In collecting the Echinidæ, much caution is required in dissecting specimens surrounded by spines. If imbedded in hard limestone, or in laminated clay,

it is scarcely possible to succeed; but it often happens that the Cidarites of the Oolite are attached by the base to the solid limestone, and the body with the spines is imbedded in clay, or in a sandy, friable aggregate, not difficult of removal. The specimen in my cabinet, with upwards of fifty of these appendages attached to the shell, was obtained under such circumstances. The Chalk Echini will be found to possess spines more frequently than is commonly supposed, if care be taken to explore the surrounding stone before it be removed. I have often obtained Cidarites with the spines, when there were no manifest evidences of these appendages, by carefully scraping away the surrounding mass until the extremity of a spine appeared, and then tracing it to the body of the shell; another point was discovered by further removal, and that was developed in the same manner; till at length a Cidaris with several spines was disclosed. The chalk around the situation of the mouth should always be cautiously removed in the dentated species, in the hope of preserving the teeth, as in the specimens Lign. 77, fig. 1, and Lign. 79, fig. 1.

As the shells of Echinites, when hollow, are often lined with crystals (see Lign. 82, fig. 3.), it is worth while to break all indifferent specimens of the common species, in the hope of discovering such examples.

The chalk must not be scraped, from the crust or shell of the Echinites, or the minute papilla will be

injured or removed; it should be flaked off piecemeal with a blunt point.

In loose arenaceous strata, as in some of the Maestricht and Tertiary deposits, the Echinites may be extricated in as perfect a condition as if fresh from the sea; and it is probable, from the known habit of these animals of burrowing in mud and sand, that they still occupy their original situations, and were entombed alive by the sediment in which they are now imbedded.

The student may always procure from the dealers named at the end of this work, specimens of the common fossil species of Echinoderma, at moderate prices.