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Brazils diamonds occur in breccia, composed of quartzose and opaline pebbles, united by an arenaceous ferruginous cement; in Bundel Kaand, in sandstone, supposed to belong to the Triassic deposits, for there are strata of that age 400 feet in thickness beneath the lowest diamond beds, and indications of coal underlying the whole.1

ALGE, FUCI, &c.-Case A.-Remains of several kinds of vegetables of the simplest structure, as Fuci, Algæ, Fungi,

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LIGN 1.-FOSSIL FUCUS IN MALM-ROCK, BIGNOR, SUSSEX.
Fucoides Targionii.
(NAT. SIZE.)

&c., occur in a fossil state, and even some minute parasitical species have been detected on the leaves of fern in coal shale.

1 See" Wonders of Geology," 6th edit. pp. 703-706, for an account of Amber, Diamond, Bitumen, Petroleum, Anthracite, Plumbago, &c.; "Medals of Creation," vol i. p. 83.

A most important acquisition has very recently been made to the Cabinet of Diamonds; an unique series of crystallized specimens, purchased of Professor Tennant, comprising upwards of sixty examples of rare modifications of form, and of various colours. It formed part of the celebrated cabinet of precious stones formed with great taste and judgment, and regardless of expense, by the late Henry Phillip Hope, Esq. Of the cubic crystal there are six; of the octohedron, sixteen or eighteen; of the hemitrope, or macled crystals, four; of grouped crystals, thirty. This most interesting suite of gems includes also several fine specimens of what are termed "diamonds of nature," which are diverging fibrous concretions of this crystalline substance. A model of the matchless Indian diamond, known as the Koh-i-noor, or Mountain of Light, and now exposed to public view in the Great Exhibition, by Her Majesty's gracious permission, will shortly be added to this unrivalled collection.

The case, A, contains several species of Algæ and Fuci, and many fossil plants belonging to a higher class, but whose natural affinities are not accurately determined. Much of the space is occupied by fossil ferns, and specimens of a common and elegant tribe of coal-plants (named Asterophyllites, Annularia, &c.), whose verticillate foliage is too remarkable to escape notice, and is often seen on the slabs of coal-shale associated with ferns.

Fucoides. Of fossil fuci there are specimens from Bignor, in Sussex, of a species peculiar to the firestone of the chalk formation, the Fucoides (Chondrites) Targionii; and an elegant species named Fucoides arcuatus. With the fucoides are specimens of fossil algæ, labelled Spherococcites, which are sea-weeds with thick membranous and coriaceous fronds, divided into digitated lobes, wide or narrow, often irregular and elongated, without nervures, and with a smooth surface, bearing irregular tubercles; from the Oolite of Solenhofen.

On the shelves there are pieces of ironstone with vestiges of carbonized vegetables, from the Wealden (of Heathfield, Sussex), some of which are probably referable to fresh-water aquatic plants; others to trees allied to the yew or cypress (Thuyites).

Asterophyllites.-Case A.-The specimens of elegant foliage on slabs of coal-shale, labelled Asterophyllites, Annularia, and Sphenophyllum, belong to a tribe of extinct dicotyledonous plants, which, like the existing Cycadeæ, had their seeds exposed; hence the name of the order, Gymnosperms, or naked seeds.

The Asterophyllites, so named from the star-like disposition of their foliage, had branched articulated stems, with verticillate leaves arranged perpendicularly to the branches which supported them; but as the foliage is in most examples partially imbedded and concealed in the stone, the natural appearance of the plant is but seldom observable. The fossils known as Volkmannia are now ascertained to be Asterophyllites in fructification.

The Annularia were herbaceous plants, with verticillate foliage, like the former; but the whorls were arranged on

1 Figured in " Medals of Creation," p. 152; and "Wonders of Geology," 6th edit. p. 717.

the same plane with the stems whence they proceeded, and, in consequence, their remains present a very elegant appearance when expanded on the schist. Each whorl is composed of from twenty to thirty linear lanceolate leaves, which are united at their base, so as to form a zone around the stem: it is supposed that they were aquatic, or marsh plants, the stems and leaves floating on the surface of the water. Both these extinct types of plants are common in the carboniferous strata.2

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LIGN. 2.-ANNULARIA: IN COALSHALE. (nat.size.)

[blocks in formation]

LIGN. 3.-EQUISETUM LYELLII. POUNCEFORD.

Fig. 1. Stem with two sheaths, and a head at the lowermost joint.

2. Stem of a young plant, pyritified.

3. Stem with the cryptogamous head. (Nat. size.)

EQUISETACEA.-Case A.-Fossil plants allied to the Equisetum (Mare's-tail). The family of the Equisetacea comprises

1 See "Tableau des Genres de Végétaux Fossiles." Par M. Adolphe Brongniart. Paris, 1849.

2 Plate V. of "Pictorial Atlas of Organic Remains" contains coloured figures of both genera.

but one genus, the common species of which (Eq. fluviatile) abounds in marshy tracts, and on the banks of our ditches and rivers. It has a jointed stalk, encircled by elegant cylindrical dentated sheaths, and garnished with verticillate linear leaves. In a fossil state several species of this genus are known, of which there are specimens in Case A. Those of the Equisetum Lyellii, from Pounceford in Sussex, were collected by the Author in 1825. This species is peculiar to the Wealden deposits; it has a cylindrical and articulated stem, the articulations of which are embraced by regularly dentated sheaths. It was a slender elegant plant, of the proportions of the common existing Mare's-tail.i

EQUISETITES.-Case B.-These are the stems of gigantic equisetaceous plants, which, though allied by their general characters to the diminutive existing Equisetum, differ in some essential particulars. They are named by M. Brongniart, the eminent botanist, Equisetites. These stems are from twenty to thirty feet in height, and from ten to fourteen inches in diameter. The surface is smooth, not striated, and is not impressed by the denticulations of the sheath, as in the Mare'stail. The fructification is unknown. These plants, of which there are many specimens in Case B. (of Eq. columnare, Eq. laterale, &c.), are common in the inferior oolite of Yorkshire, and are frequently discovered in an upright position. Extensive areas covered by the roots and erect stems, apparently occupying the spots where they originally grew, have been laid bare in the Cleveland Hills. A few freshwater bivalves are the only fossil-shells observed in the laminated sandstone in which the stems are imbedded.

CALAMITES.-Case B, Upper Shelves.-These large stems belong to a tribe of plants which abounded in the carboniferous epoch, and must have constituted an important feature in its flora, for their remains are abundant in the coal deposits of every country. Though bearing a general resemblance to the Equisetacea, they are entirely distinct; their stems are articulated and regularly striated, and sometimes arborescent; the articulations are in general marked with annular depressions, and studded with tubercles; in

1 Pounceford, near Burwash, in Sussex, is an interesting locality of the Wealden. See "Geology of the South-East of England," p. 221.

some examples, there are remains of a stellate sheath encircling the joints, but this is altogether different from the

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cylindrical sheath of the Equisetaceæ. The stems often attain a height of forty or fifty feet, and a diameter of from one to three feet. When specimens are lying in the same plane with the lines of stratification, they are generally pressed flat; but when found in an erect position, they retain their natural cylindrical form. The bark, in the state

of a carbonaceous crust, frequently invests the stem; but I have not been able to detect any traces of internal structure. The axis of the stem appears to have perished, and its place is occupied by clay or sand. Vestiges of the roots are sometimes preserved.' The case comprises several species: as Calamites approximatus, C. canniformis, C. nodosus, C. decoratus, &c.

1 Specimens are figured in "Medals of Creation," p. 110; and seven species in "Pictorial Atlas of Organic Remains," Pl. XIII-XVII.

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