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fossils in Cases D, E, and F, which are respectively labelled Lepidodendron, and Stigmaria.

Besides the fine specimens of Stigmariæ in the cases above referred to, there is an instructive example of these trailing

LIGN. 13.-PORTION OF A BRANCH OF LEPIDODENDRON: IN COAL SHALE,

NEWCASTLE.

Fig. 2. A scar of a petiole. (Nat. size.)

roots, twenty-six feet long, attached to a board, placed over the doorway of Room I. at the entrance from the Zoological Gallery.

Calamitia.-Case E.-On the left hand of the lower compartment, there are placed on some shallow ledges, many specimens of the silicified stems named Calamitia by M. Cotta,

and Calamodendron by M. Brongniart. These are the remains of plants altogether different from any known living vegetables in their internal organization. The disposition of the ligneous cylinder and of the medullary rays, indicate a dicotyledonous structure; but the vascular tissue approaches that of the gymnosperms, and is still more analogous to that of the Sigillariæ.

LYCOPODIACEE-(Lepidodendron, Lepidostrobus, Lepidophyllum).-Cases C, D, E.-The upper compartments of these cases [marked 3, 4, and 5, in the

room] contain a rich assemblage of the stems, leaves, and fruits, of a gigantic tribe of club-mosses (or Lycopodiaceae), named Lepidodendron (or scaly-tree), from the triangular scars of the petioles with which the surface of the stem is covered. These plants rivalled in number and magnitude the Calamites and Sigillariæ, and their remains are profusely distributed in the coalshales, occurring, like the stems of the former, both erect and cylindrical, and prostrate and compressed, as in the examples before us. Some of these trees have been discovered almost entire, from their roots to the topmost branches. Near Newcastle in the Jarrow coal-mine, a tree was laid bare that measured forty feet in height, and above thirteen feet in diameter at the base; it divided towards the summit into about twenty branches. The foliage (Lepidophyllum) of these trees consisted of simple linear leaves, spirally arranged around the stem; and these

[graphic]

LIGN. 14.

A tree 39 feet high, and 133 feet

appear to have been shed from the LEPIDODENDRON STERNBERGII. base of the trunk by age. The scars wide at the base. Coal mine, Newproduced by the attachment of the castle.

petioles were persistent, and are seldom obliterated in the

fossils; the branches and twigs are generally covered with foliage.1

Lepidostrobus.-Case D.-The seed-vessels are cylindrical cones composed of winged scales, their axis being traversed by a longitudinal cavity or receptacle, and terminating in rhomboidal disks, imbricated from above downwards. They occur of various sizes-from two to six inches long, and one or two inches in circumference. These fruits, like the fronds of ferns, often form the nuclei of the ironstone nodules so abundant in the carbonaceous clays, and are frequently mineralized by brilliant pyrites, and galena or sulphuret of lead. There is a beautiful suite of these fossils (the greater part from the Author's collection) in Case D: they were obtained from Coalbrook Dale. When imbedded in the rock, the cones are often fringed with linear-lanceolate bracteæ.

Notwithstanding the great disparity in size between the existing family of club-mosses or Lycopodiaceæ, most of which trail on the ground, and none exceed three or four feet in height, and the Lepidodendra, M. Brongniart, Dr. Joseph Hooker, and other eminent botanists, concur in regarding these gigantic trees of the coal flora as belonging to the same tribe, and only generically distinct."

The visitor's attention should be directed to the beautiful specimens of Lepidodendron selaginoides on coal-shale, on the upper shelf of Case D; and of L. punctatum.

Ulodendron, Bothrodendron, Halonia, Megaphyton.-Case E. The specimens to which these names are attached, are the stems of plants belonging to the same family as the Lepidodendra, but supposed to be generically, or sub-generically, distinct. The Bothrodendron (pitted-stem) is remarkable for two vertical rows of deep oval depressions, on opposite sides of the stem, which more resemble the attachment of the bases of cones, than of leaves. In Megaphyton the stem is not furrowed, the leaf-scars are very large and of a horse-shoe form, and disposed in two vertical rows on each side.3

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1 Figured in "Medals of Creation," pp. 146, 149; Wonders of Geology," p. 718; " Pictorial Atlas," Pl. I. III. IX. XXVI. XXVII. XXXIII. The botanical reader interested in the subject is referred to "Memoirs of the Geological Survey of Great Britain," vol. ii.; and "Dict. Univ. d'Hist. Nat.," Article, "Tableau des Genres de Végétaux Fossiles," Paris, 1849.

3 "Pictorial Atlas," Pl. XXV.

On the uppermost shelves are the Halonia; these fossils are sandstone casts with a thin carbonaceous crust, of cylindrical stems, which are beset with large elevated knobs or projections disposed in quincunx; these are not produced by the attachment of petioles, but are sub-cortical protuberances : the botanical affinities of these plants are not satisfactorily determined.1 Sternbergia; Artesia.-Case E.-The fossil stems thus labelled are on the shelves below the Haloniæ ; they are supposed to be the carbonized medullary axis of a genus of plants distinct from the Lepidodendra, and named Lepidophloios by Count Sternberg.

2

THE CARBONIFEROUS FLORA.—Although there are vestiges of many coniferous trees, and of some endogenous plants, in the coal-strata, yet as the vegetables we have cursorily examined constitute the essential features of the flora of the carboniferous epoch, a few general remarks on the subject will not be irrelevant in this place.

The peculiarity of this flora is the great number of the vascular cryptogamous plants, which amount to two-thirds of the species of vegetables discovered in the carboniferous deposits. With these are associated a few palms, coniferæ, cycadeæ, and some dicotyledons, allied to the cacter and euphorbiaceæ. The magnitude and numerical preponderance of plants analogous to the Ductulose, but differing in species and genera from existing forms, constitute, therefore, the most striking botanical feature of the flora of this epoch. Thus we have trees allied to the equisetaceæ, thirty or forty feet high, and eighteen inches or more in circumference (Calamites); arborescent club-mosses (Lepidodendra), attaining an altitude of sixty or seventy feet; and zamia-like coniferæ (Sigillaria), fifty feet high. Of these ancient and extinct types, the latter tribe is especially remarkable in consequence of the peculiar circumstances under which the erect stems and roots occur, and which it will here be necessary to consider, as the phenomenon is highly interesting, and bears strongly on the question as to the mode in which the beds of coal, clays, and shales, that

1 Figured in " Medals of Creation," p. 150.

2 See M. Brongniart's "Tableau de Vég. Foss." p. 43; "Pictorial Atlas," Pl. XVIII.

constitute the deposits termed coal-measures, were accumulated. Every coal-field (as a group of these strata is generally termed) is composed of a succession of a triple series of beds; viz. firstly, the lowermost a tough argillaceous earthy stratum, termed under-clay, on which the bed of coal invariably rests; and it is in this deposit that the roots (Stigmaria) of the trees are always found, and commonly parallel with the plane of the strata; these are generally the only vegetable remains contained in this bed, though the clay is occasionally black from an intermixture of carbonaceous matter. Secondly, the coal, which is composed of the stems and foliage of trees transmuted into a bituminous carbonized mass large stems, branches, or leaves, are but seldom found in it. Thirdly, the roof, or overlying stratum, consisting of slaty clay, and water-worn detritus of other rocks transported from a distance, and full of detached leaves, and flattened and broken trunks and branches: it contains layers and nodules of ironstone enclosing leaves, insects, and crustaceans. In some localities beds of fresh-water shells-as mussels, in others marine shells, are intercalated: finely laminated clays, micaceous sand, grit, pebbles of limestone and sandstone, are sometimes imbedded in it. Thus it seems probable that the under-clay is the natural soil in which the coal-trees grew, the roots often remaining in their original position and spreading out from the trunk: the coal is formed of the carbonized stems and foliage; and the roof, or upper bed of shale and clay, is composed of the leaves and branches of a forest that was overwhelmed and engulfed beneath an accumulation of transported detritus.'

PSAROLITES or PSARONIUS.-Cases C, D, E. Lower Shelves. [3 to 5.]-On these shelves is an extensive series of silicified stems, many of them cut transversely and polished; the specimens labelled as above are chiefly from the Triassic or New Red Sandstone deposits of Chemnitz, near Hillersdorf, in Saxony. They are portions of petrified trunks of trees. allied to the arborescent ferns and club-mosses, and possess a remarkable internal structure, that is exquisitely preserved in many of the petrifactions before us. The transverse sections

1 For a full consideration of this subject see "Wonders of Geology," pp. 669, 718, 731: "Pictorial Atlas of Organic Remains," p. 181.

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