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FILICITES, OR FOSSIL FERNS.-Cases A. B. C. [1, 2, 3.]—This numerous and interesting tribe of vascular cryptogamous plants, the living species of which confer a peculiar elegance on the flora of the countries in which they abound, prevailed in great numbers and variety during the carboniferous period; several hundred extinct species, belonging to many genera, have been determined. Ferns are distinguished from other vegetables by the peculiar arrangement of the veins of the fronds, and the development, in most species, of the fructification on their leaves. Although the largest British species scarcely exceeds four or five feet in height, many of the tribe peculiar to hot climates are arborescent, and attain an altitude of thirty or forty feet; their stems are cylindrical and without branches, and the foliage spreads out from the summit of the tree and expands into an elegant canopy. The leaves on the stems are not persistent, and the petioles soon become detached from their base, and leave permanent cicatrices, or scars, on the trunk; and these imprints are so durable, and so symmetrically arranged, as to afford characters by which the stem of a tree-fern may easily be recognised in a fossil state; for though the stem may be pressed quite flat, and its foliage entirely wanting, the configuration and disposition of the scars afford a certain means of identification. The leaves are characterised by the form, regularity, and peculiar mode of subdivision of the segments, and by the delicacy, evenness, and distribution of the veins or nervures. From the elegance and diversity of form of the foliage, fossil ferns are the most remarkable and attractive vegetable remains in the ancient strata; and in the collection before us, a considerable number of the most important and characteristic species are exhibited. The greater part are from the coal deposits, the fern-leaves generally occurring in the schists or shales that form the roof of the beds of coal.1 Many of the strata of shale are made up of carbonized fernleaves and stems closely pressed together. The roof of a coal mine, when newly exposed, often presents the most interesting appearance from the abundance and variety of leaves, branches, and stems, that appear sometimes in relief, sometimes im

'See "Wonders of Geology," Sixth Edition, pp. 666-677: "On the nature of Coal Deposits."

pressed, on the dark shining surface. When the shale or stone is of a light colour, the contrast of the black carbonized foliage increases the striking effect of these subterranean floras of the ancient world. The specimens in coal-shale exhibited in Cases B and C, are for the most part from the coal-shales of Great Britain; the series comprises a considerable number of the genera, and many of the species that have been identified by M. Brongniart, Sternberg, Lindley, Hutton, and other eminent botanists. (Pecopteris, Pachypteris, Sphenopteris, Cyclopteris, Neuropteris, Glossopteris, Odontopteris, Phlebopteris, &c.')



Figs. 1 and 2. Leaflets magnified to show the venation.

FERNS of the WEALDEN.-Case B.-There are here specimens of two species of fern which require especial notice, because they were obtained from the ancient freshwater deposits of the south-east of England-the Wealden-associated with the reptilian remains of which we shall have occasion to treat hereafter.

Lonchopteris.-One of these, named Lonchopteris (L. Mantelli), from the spear-shaped fronds, is characterised by the peculiar reticulation of the venation. There are three fossil

1 See "Medals of Creation," vol i. pp. 113-124, for figures and descriptions of these genera of fossil ferns. Several kinds are represented in the "Pictorial Atlas," pp. 4, and 28-32 inclusive.

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species of this genus, and these resemble the living ferns of the genera Lonchitis and Woodwardia; two occur in the Coal deposits; the other, the one under consideration, in the Wealden and Greensand. The latter appears to have been a delicate plant, for though vestiges of the carbonized foliage are very generally distributed through the Wealden deposits, it is rarely that any considerable portion of a frond can be obtained.

Sphenopteris.-The other characteristic Wealden plant is the Sphenopteris (S. Mantelli), or wedge-leaf fern, remarkable for its elegant and simple fronds, as shown in the annexed figure. (Lign. 6.). ANOMOPTERIS MOUGEOTTI.-Case B.-On the front of one



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Fig. 1. Portion of a frond in fructification.


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of the middle shelves, on a block of fawn-coloured sandstone, are remains of the foliage of a large species of fern, labelled as above. These fossil leaves are remarkable for their peculiar structure and great size some specimens are estimated to have been three or four feet in length; they are supposed to be the foliage of an arborescent fern. This species is only known in the Triassic formation of the Vosges. The specimen in the Museum shows the fructification, and was collected and

LIGN. 7.-ANOMOPTERIS MOUGEOTTI. THE TRIAS. presented to me by the

2. A part of the same magnified.

late M. Voltz of Strasburg.

FERN-STEMS (Caulopteris).-Case D.-Flattened stems, marked with discoidal, oblong, or ovate scars, arranged longitudinally; these are in all probability the trunks of the arborescent ferns whose foliage abounds in the carboniferous deposits.

SIGILLARIA. Case C. Upper Shelves.-Among the most common and striking objects that arrest the attention of a person who visits a coal-mine for the first time, and examines the fossil vegetable remains which lie profusely scattered among the heaps of shale, are long, flat, narrow slabs, with a black glossy surface, fluted longitudinally, and uniformly pitted with deep symmetrical imprints, disposed with great

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regularity between the grooves. There are many fine specimens on the upper shelf in Case C. These slabs are commonly from half-an-inch to an inch in thickness, and have similar markings on both sides. They are the flattened trunks of large trees covered by the bark in the state of coal, the markings on the surface being the scars left by the separation of the leaf-stalks, like the cicatrices on the stems of arborescent ferns. The name Sigillaria has been given to these trees from


the uniformity of the imprints suggesting the idea of impressions made by a seal. The stems vary from a few inches to several feet in diameter, and attain a length of fifty or sixty feet. They are often found erect, and uncompressed; in general, all vestiges of internal structure are lost, the cylinder of carbonized bark being filled up with clay or sand, and giving rise to large cylindrical casts of stone, slightly impressed with the longitudinal furrows and leaf-pits. A few examples of silicified stems have been discovered, and by sections, and a microscopical examination of these fossils, the internal organization of these remarkable extinct types of vegetation has been ascertained. The Sigillariæ were tall erect trees, with a regular and cylindrical stem, having no side branches, but becoming dichotomous at the summit. Their superficial bark was hard and durable, channelled longitudinally, bearing leaf-scars that are of a rounded form above and below, and angular at the sides, often oblong in relation to the stem, and having three vascular pits, one central and small, and two lateral of a larger size. The internal structure bears most analogy to that of the Cycadeæ, and the foliage consisted of long linear carinated leaves. The Sigillariæ, therefore, differ essentially from the arborescent cryptogamia, which they somewhat approach in having scalariform vascular tissue, symmetrical and regular leaf-scars, and branchless trunks. More than fifty species have been determined.1

Sigillaria (or Sagenaria) caudata.-Case C.-On the front of the middle shelf of this case, immediately above the label— Filicites there is a sandstone cast of an uncompressed Sigillaria, deeply imprinted with the cicatrices left by the petioles, which is remarkable for the extraordinary sharpness of the scars, and the geological position ascribed to it. It was discovered (as I was informed by the Dean of Westminster, when examining with him the fossil plants in this case) in the Greensand, which is the lowermost group of the chalk formation. Now, as the Sigillariæ are peculiar to the carboniferous epoch, no other instance being known of any vestiges of this tribe of vegetables in subsequent deposits, it is

1 Figures of Sigillariæ in "Wonders of Geology," p. 719; "Medals of Creation," p. 129, Pl. V.; "Pictorial Atlas," Pl. XÎX., XX., XXIV.

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