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important that the habitat of this fossil should be ascertained, and its geological age determined.

STIGMARIA. - Cases E, F.- On the upper shelves of these cases are deposited numerous specimens of certain fossil vegetables which are abundant in most coal fields, and are commonly known as Spotted-stems, or Stigmariæ. These bodies, when uncompressed, are of a cylindrical form, from one to six or seven inches in diameter, and of great length-sometimes twenty or thirty feet-gradually lessening, and dividing and subdividing, as they extend. The surface is marked with distinct pits or areola, which are either oval

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Fig. 1. Portion of a root. (nat. size.) The internal axis is seen at a.

2. One of the rootlets, with a tubercle, to show the mode of articulation.

or circular, with a slight elevation or tubercle in the centre of each; they are disposed around the stem in a quincunx order somewhat regularly. When these fossils are observed in situ, or are compressed and imbedded in shale or stone, as in some of the specimens in Case F, long, tapering, subcylindrical fibres, are seen to proceed from the pits or depressions with which the surface is studded, each being attached by its base to the tubercle or eminence in the centre of the areola. When

broken transversely, a small cylindrical core or axis is found extending longitudinally throughout the stem like a medullary column, (a, Lign. 9.) and there is generally a depression or furrow running parallel with it on the outer surface.1

The nature of these fossil vegetables was long a perplexing question, for no specimens had been found in connexion with any of the stems, branches, or foliage, that abound in the coal deposits. At length, the discovery of a dome-shaped mass, from which radiated numerous stigmariæ, seemed to afford a clue to the solution of this botanical problem, and it was concluded by the eminent Authors of the "Fossil Flora of Great Britain," that the original belonged to a tribe of plants which inhabited swamps, or still and shallow lakes, and were characterised by a low truncated stem, having long horizontal branches beset with cylindrical, and, probably, succulent leaves, that either trailed on the surface of the swamp, or floated in the water.2

But within the last few years, the occurrence in various carboniferous deposits, of erect stems of Sigillariæ, has shown that the Stigmariæ are nothing more than the roots of these and other congenerous trees; an opinion maintained by the Rev. H. Steinhaur more than thirty years ago, and subsequently affirmed by M. Adolphe Brongniart, who found, on examining microscopically the internal structure of a silicified specimen in which the vascular tissue was preserved, that the organization bore as close an analogy to that of the Sigillariæ, as exists between the roots and trunks of certain dicotyledonous trees.3

Upright stems of Sigillarice, with Stigmaria-roots.-To the sagacity and persevering researches of Mr. Binney of Manchester, science is indebted for the establishment of this highly interesting fact. In 1844, Mr. Binney discovered at St. Helen's, near Liverpool, an erect trunk of a Sigillaria nine feet high, to which were attached ten roots that extended several feet into the under clay, in their natural position, and

1 Figured in "Medals of Creation," p. 140, Pl. III. fig. 1; "Pictorial Atlas," Pl. XXI.-XXIII.

2 It is to be regretted that this erroneous conjecture is reprinted from Dr. Buckland's Essay, in the recent work of Messrs. Chambers on the British Museum, p. 251.

3 See "Medals of Creation," p. 143.

these roots were unquestionable Stigmariæ; the tubercles with the attached rootlets (the supposed leaves), being clearly

LIGN. 10.-ERECT STEM OF SIGILLARIA WITH STIGMARIA-ROOTS; IN A COAL-MINE IN NOVA SCOTIA.
(nat. size.)

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This stem is a solid cast in claystone, the carbonized bark retaining the characteristic markings, only remaining in a few places.

c, the decorticated part of the stem, which is covered with minute scales as far as the point h, which is a few inches below the first ramification of the roots. The carbonaceous crust that enveloped the roots was thick at the upper part, but gradually became thinner towards the extremities, and at a, and b, was a mere pellicle that fell off on the slightest touch.1

1 Journal of the Geological Society of London, 1847 and 1849.

displayed and on the floor of the Victoria mine at Dunkinfold, near Manchester, at the depth of 100 feet, Mr. Binney

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LIGN. 11.-STEM OF A SIGILLARIA BROKEN OFF CLOSE TO THE ROOTS.

In a coal mine at Cape Breton, Nova Scotia.

a, the depression left by the remo al of the stem.

(nat, size.)

laid bare a magnificent trunk of a Sigillaria, with Stigmariaroots extending upwards of twenty feet in the clay.

In the Pictou coal-field of Cape Breton, in Nova Scotia, many similar instances have been brought to light; the remarkable phenomenon existing in that locality, of successive

carboniferous deposits containing scores of erect trees with their roots spreading into their native soil, presenting peculiar facilities for verifying the observations made in England. In an interesting memoir on the coal-fields of Nova Scotia, Mr. Richard Brown has given a detailed account of numerous examples of stems of Sigillariæ, and of Lepidodendra, (a tribe of gigantic club-mosses of which we shall treat in the sequel,) with the roots attached; these roots having, in every instance, the character and structure of Stigmariæ. The annexed figure (Lign. 10) represents an erect trunk of Sigillaria alternans, with roots (Stigmaria) extending into the surrounding clay.

In another example (Lign. 11.) discovered by Mr. Brown, the stem of the tree was broken off close to the roots, and the hollow cylinder of bark (a,) was bent down and doubled over by the pressure of the surrounding mud, so as effectually to close up the aperture, and leave only a few irregular cicatrices converging near the apex; the structure, arrangement, and number of the tap-roots, as well as the horizontal ramifications, were similar to those in Lign. 10. This fossil explains the true nature of the " dome-shaped" plant figured in the Fossil Flora, and in Dr. Buckland's Essay.'

I subjoin another sketch from the same memoir in illustra

Roof of Shale full of leaves, &c.

-16 feet

Main coal seam, 6 feet thick.

Under clay with Stigmariæ.

LIGN. 12.-STEM OF A LEFIDODENDRON, WITH STIGMARIA-ROOTS.
(From Mr. Brown's Memoir.)

tion of this subject: the stem of a Lepidodendron with roots, which are Stigmariæ.

The stems and the roots of this tree were similar to the

1 See "Pictorial Atlas of Organic Remains," pp. 198-202.

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