Fucoides, of many species, are exceedingly abundant in the silurian or transition formations, from the coal series down to the primitive rocks. In certain portions of the silurian series of North American rocks, this class of plants is surprisingly prevalent, and characteristic. The oldest of these formations present us with nothing but cellular-leaved marine plants. Many species of fucoides in the copper slate of Mansfeld.

The prevailing vegetable forms of the chalk formation are those of marine and freshwater plants-fuci and najades.

Of confervæ are three fossil species; of Algæ, nine species; and of Naiades, four species, in the cretaceous group.

Distribution of Fossil Vegetation.-M. Alex. Von Humboldt has stated in a recent work, that it is in the Devonian strata that a few cryptogamic forms of vascular vegetables, equisetacea and lycopodiaceæ, are first encountered. After these strata, we arrive at the coal formation, the botanical anatomy of which has made such brilliant progress in recent times. These comprise nearly four hundred species, including in their number not only fern-like cryptogamic plants, and phanerogamous monocotyledons, grasses, yucca-like lilaceous vegetables, and palms, but also gymnospermic dicotyledons, coniferæ and cycadeæ. Fossil coniferæ have been found in the old coal formation of England and Upper Silesia; while cycadeæ are contained in that of Radnitz, in Bohemia, and Königshütte, in Upper Silesia. The cycades attain their maximum in the Keupfer strata and the lias, where about twenty different forms make their appear

ance.

The lignitic or brown coal strata, which are at present in every one of the divisions of the tertiary period, amongst the earliest forms of cryptogamic land plants, exhibit a few palms, many conifere with distinct annual rings, and frondiferous trees, of more or less decided tropical character. In the middle tertiary period we observe the complete recurrence of the palms and cycadeans; and in the last members of this epoch, at length, strong resemblances to our present flora. We come suddenly upon our pines and firs; our cupuliferous tribes; our planes, and our poplars. The dicotyledonous stems of the lignites are frequently distinguished by gigantic thickness and vast age. A trunk was found near Bonn, in which Noggerath counted 792 annual rings.

With relation to coal vegetation, M. Humboldt remarked that where several series of coal strata lie over one another, the genera and species are not always mixed; they are rather, and for the major part, generically arranged, so that only lycopodites and certain ferns occur in one series of beds, and stigmariæ and sigillariæ in another.*

In elucidation of the progress made in fossil botanical discovery, Mr. Adolphe Brongniartt has lately observed that the further we proceed in the series of ages towards the earliest geological periods,

⚫ Cosmos.

Comptes Rendu, Dec. 29th, 1845-and Annual and Mag. Nat. Hist., February, 1846.

the further are we removed from the actual creation, and the greater do the differences between the living and fossil beings become. Thus, most of the fossil plants of the tertiary strata belong to genera in actual existence, and merely present specific differences.

Those of the secondary strata may, undoubtedly, almost always be referred to known families, but appear in most cases, to require the formation of new genera.

Lastly, in the older strata, particularly in the coal formations, many of the fossil plants cannot be classed in families at present existing, and ought to constitute new groups of equal importance.

He adds that new and hitherto very rare specimens, which have been collected and carefully studied in England, Germany, and France, have caused important changes relative to the plants which he had previously considered as vascular cryptogamia. This advance is owing to the discovery of portions of stems of these plants having the internal structure in a state of preservation. They have shown that the sigillariæ, stigmariæ, and probably most of the calamites, are not plants nearly related to the ferns, lycopodia, and equiseta, but to distinct families of the dicotyledonous gymnospermous group, more nearly approaching the coniferee and cycadex.

Hence, at the period of the coal formation, vegetation would have consisted entirely, or nearly so, of two of the great divisions of the vegetable kingdom: the ACROGENOUS CRYPTOGAMIA, represented by the herbaceous and arborescent ferns, [the latter reduced to the true caulopteris,] the lepidodendreæ, a family nearly related to the lycopodiacea, and some equisetacea; and the GYMNOSPERMOUS DICOTYLEDONS, comprising the sigillariæ, [sigillaria, stigmaria, lepidofloyos,] the calamitacex, the coniferæ, and probably the asterophylleœ, [asterophyllites, annularia, and sphenophyllum.]

Mr. Brongniart proceeds to describe a plant which closely approaches a family of the gymnospermous dicotyledons still in existence, the cycadex, and of the genus noggerathia. This plant, at first known to M. de Sternberg, by the impression of a single leaf, from the coal formation of Bohemia, has since been observed in the coal shales of Newcastle, in those of Silesia, in the Permian sandstones of Russia, and many new species of the same genus are in the schists and coal sandstones of France.

He considers, with M. Humboldt, that each stratum of coal is the product of a peculiar vegetation, frequently different from that which precedes and that which follows it,-vegetations which have given rise to the superior and inferior layers of coal; each stratum resulting, in this manner, from a distinct vegetation, is frequently characterized by the predominance of certain impressions of plants, and the miners, in numerous cases, distinguish the different strata, which they remove, by the practical knowledge they possess of the accompanying fossils. Any seam of coal and its overlying rock or slate, should consequently contain the various parts of the living plants at the period of its formation; and by carefully studying the association of these various fossils, which form so many special floras, containing

generally but few species, we may hope to be able to reconstruct these anomalous forms of the ancient world.,

Distribution of fossil plants.-Notes from the Quarterly Journal of the Geological Society of London, Vol. I., 1845, p. 566, and Vol. II., 1846, p. 83.

The following extract, [with some modifications derived from Mr. Murchisson's paper on the Permian system,] from a memoir by M. Goeppert, of Breslau, well known for his investigations concerning the fossil remains of vegetables, possesses great interest, as offering a general view of the relative distribution of these remains.

Formations.

Lower Paleozoic System:

Grauwacké, silurian, or formations older than the carboniferous series, including the Devonian series, and the oldest coal or culm beds,

Permian system, or Upper Palæozoic:

Carboniferous limestone,

True coal measures of Europe and North America, Lower new red sandstone, Permian series, containing, among others, a few species common to the carboniferous era,

Magnesian limestone and kupfer schiefer, chiefly marine fucoids, Permian system,

Gres bigarré, Bunter sandstein,

Triassic period; or Lower Secondary:

Muschelkalk,

Lower Tertiary.-Monte Bolca beds,

Other lower, tertiary,

Middle and upper tertiary.-Miocene and pliocene,

Unknown geological position,

Families. Species.

Older Palæozoic rocks below the coal mea

sures,

Coal measures,

Newer Palæozoic or Permian system, above, 15

Triassic and secondary formations,

90

55

366

66

454

Tertiary,

Unknown,

Recapitulation.

Summary of M. Geppert's numerical distribution of Fossil plants. -The following table presented by Sir R. T. Murchisson at the meeting of the British Association, in 1845, embodies the same facts as are already announced in detail above.

It was further stated, that the number of fossil plants known to M. Adolphe Brongniart, in 1836, was 527. In the new list they amount to 1792! and it is seen that the carboniferous group contained more than half the known species of fossil plants; a remarkable circumstance, when it was considered that the great herbivorous land quadrupeds had no ascertained existence before the tertiary period.*

For a notice of the flora and fauna of the amber forests of the countries bordering on the Baltic, our readers are referred to the head of Prussian Pomerania, in this volume.

MICROSCOPIC OBSERVATIONS ON THE STRUCTURE OF COAL, LIGNITE AND PEAT.

Among other collateral subjects of interest, tending to throw light on the age, the history and the composition of coal, the mode of investigation through the agency of the microscope, is not altogether inappropriate.

Mr. Hutton, of Newcastle, has instituted a series of examinations of the substance of coals, through the aid of the microscope.

Professor Phillips addressed some observations to the British Association, in 1842, on this new test.

In consequence of the facilities afforded for polishing coal, and of examining it by means of transmitted light, some progress has been made in this mode of investigation.

By the process of combustion another method had suggested itself, for making apparent to the eye the vegetable tissues of which certain coal plants were composed. In the ashes of Staffordshire coal,-a variety not strictly bituminous or caking,-Mr. Phillips was impressed with the analogy they presented to the combustion of certain sorts of peat, of a laminated texture; and their microscopic examination showed abundant traces of a vegetable character.

* Report of the British Association, 1845.

In some anthracite ashes furnished by Sir Henry De la Beche, vegetable tissues were also found; and the same fact is also visible in the ashes of the Pennsylvania anthracites.

A paper was read to the Geological Society of London, January 9th, 1833, entitled "Observations on Coal," by W. Hutton. The author was led to this subject by pursuing the method of microscopic examination, so successfully employed by Mr. Witham; and from these observations much interesting information has been acquired, respecting the fine, distinct reticulation of the original vegetable texture, still discernible in the various species of coal, and showing the presence, in the Newcastle coals, of cells which are filled with bituminous matter, extremely volatile.

Another system of cells was discovered, different from the others, which he conceived was adapted for containing gas. These supposed gas cells are found empty, and of a circular form, and in groups which communicate with each other; each cavity having, in its centre, a small pellet of carbonaceous matter. The author establishes a clear distinction between these two classes of cells; for the anthracite of South Wales contains the gas cells, but is quite free from those which, in the other coals, are filled with bituminous matter. The anthracite of South Wales affords a free disengagement of inflammable gas when first exposed to the air.*

Additional light is thrown on this subject by a paper of M. Link, of Berlin, "on the origin of coal and lignites, according to microscopic observations."+

The professor remarks that there still prevail two different opinions relative to the origin of coal. The one sustains the view that it is a turf, peat or marsh of the primitive world; the other that it consists of the trunks of forest trees which have been brought together and here buried.

Ordinary peat consists of earthy matter penetrated by the roots or radical fibres of vegetables, with here and there some portions of leaves. This earthy part is composed of the cellular tissue of plants, whose structure has been so flattened by pressure, that it is often impossible to recognise them.

A second and better description of peat is sold at Berlin, under the name of tourbe de linum, which consists of cellular tissue, compressed in exceedingly thin laminæ.

A third variety, dug in Lower Pomerania, has acquired the appearance of fossil wood; being compact, and its fracture conchoidal and bright; yet still containing parts which resemble the debris of leaves. There remains no trace of ligneous structure. Some portions of this peat become partially transparent when plunged in olive oil; and still more so when they are coated with rectified oil from coal tar.

By observing a similar process with regard to coals, we are enabled to render a great portion of their parts transparent. It has, in this way, been found that the lignite or brown coal of New Granada, and

Proceedings of Geol. Soc. of Lon. vol. i. 415.

† Annales des Mines, vol. xvii. p. 593. 1840.