If we take a general review of the remains of terrestrial Vegetables, that are distributed through the three great periods of geological history, we find a similar division of them into groups, each respectively indicating the same successive diminutions of Temperature upon the Land, which have been inferred from the remains of the vegetation of the Sea. Thus, in strata of the Transition series, we have an association of a few existing families of Endogenous Plants,* chiefly Ferns and Equisetaceæ, with extinct families both Endogenous and Exogenous, which some modern botanists have considered to indicate a Climate hotter than that of the Tropics of the present day.

In the Secondary formations, the species of these most early families become much less numerous, and many of their genera, and even of the families themselves entirely cease; and a large increase takes place in two families, that comprehend many existing forms of vegetables, and are rare in the Coal formation, viz. Cycade and Coniferæ. The united characters of the groups associated in this series, indicate a Climate, whose temperature was nearly similar to that which prevails within the present Tropics.

In the Tertiary deposites, the greater number of the families of the first series, and many of those of the second, disappear; and a more complicated dicotyledonous† Vegeta

occurs in Lias at Lyme Regis, and at Boll in Wurtemberg; and F. Targionii in the Upper Greensand near Bignor in Sussex.

Endogenous Plants are those, the growth of whose stems takes place by addition from within. Exogenous are those in which the growth takes place by addition from without.

+ Monocotyledonous Plants are those, the embryo of whose seed is made up of one cotyledon or lobe, like the seed of a Lily or an Onion. Dicotyledonous Plants are those, the embryo of whose seed is made up of two lobes, as in the Bean and Coffee-seed. The stems of Monocotyledonous Plants are all Endogenous, i, e. increase from within by the addition of bundles of vessels set in cellular substance, and enlarge their bulk by addition from the centre outwards, e. g. Palms, Canes, and Liliaceous plants. The stems of Dicotyledonous Plants are all Exogenous, i. e. increase externally by the addition of

tion takes place of the simpler forms which predominated through the two preceding periods. Smaller Equisetaceæ also succeed to the gigantic Calamites; Ferns are reduced in size and number to the scanty proportions they bear on the southern verge of our temperate climates; the presence of Palms attests the absence of any severe degree of cold, and the general character marks a Climate nearly approaching to that of the Mediterranean.

We owe to the labours of Schlotheim, Sternberg and Ad. Brongniart the foundation of such a systematic arrangement of fossil plants, as enables us to enter, by means of the analogies of recent plants, into the difficult question of the Ancient Vegetation of the Earth, during those periods when the strata were under the process of formation.

Few persons are aware of the nature of the evidence, upon which we have at length arrived at a certain and satisfactory conclusion, respecting the long disputed question as to the vegetable origin of Coal. It is not unfrequent to find among the cinders beneath our grates, traces of fossil plants, whose cavities having been filled with silt, at the time of their deposition in the vegetable mass, that gave origin to the Coal, have left the impression of their forms upon clay and sand enclosed within them, sharp as those received by a cast from the interior of a mould.

A still more decisive proof of the vegetable origin, even of the most perfect bituminous Coal has recently been discovered by Mr. Hutton; he has ascertained that if any of the three varieties of Coal found near Newcastle be cut into very thin slices and submitted to the microscope, more or less of vegetable structure can be recognised.*

concentric layers from without; these form the rings, which mark the amount of annual growth in the Oak and other forest trees in our climate.

"In these varieties of coal," says Mr. Hutton, "even in samples taken indiscriminately, more or less of Vegetable Texture could always

STATE OF FOSSIL PLANTS IN NEWCASTLE COAL-PITS. 343

We shall farther illustrate this point, by a brief description of the manner in which the remains of vegetables are disposed in the Carboniferous strata of two important Coal fields, namely, those of Newcastle in the north of England, and of Swina in Bohemia, on the N. W. of Prague.

The Newcastle Coal-field is at the present time supplying rich materials to the Fossil Flora of Great Britain, now

be discovered, thus affording the fullest evidence, if any such proof were wanting, of the Vegetable Origin of Coal.

"Each of these three kinds of coal, besides the fine distinct reticulation of the original vegetable texture, exhibits other cells, which are filled with a light wine-yellow-coloured matter, apparently of a bituminous nature, and which is so volatile as to be entirely expelled by heat, before any change is effected in the other constituents of the coal. The number and appearance of these cells vary with each variety of coal. In caking coal, the cells are comparatively few, and are highly elongated.-In the finest portions of this ccal, where the crystalline structure, as indicated by the rhomboidal form of its fragments, is most developed, the cells are completely obliterated.

"The slate-coal, contains two kinds of cells, both of which are filled with yellow bituminous matter. One kind is that already noticed in caking coal; while the other kind of cells constitutes groups of smaller cells, of an elongated circular figure.

In those varieties which go under the name of Cannel, Parrot, and Splent Coal, the crystalline structure, so conspicuous in fine caking coal, is wholly wanting; the first kind of cells are rarely seen, and the whole surface displays an almost uniform series of the second class of cells, filled with bituminous matter, and separated from each other by thin fibrous divisions, Mr. Hutton considers it highly probable that these cells are derived from the reticular texture of the parent plant, rounded and confused by the enormous pressure, to which the vegetable matter has been subject."

The author next states that though the crystalline and uncrystalline, or, in other terms, perfectly and imperfectly developed varieties of coal generally occur in distinct strata, yet it is easy to find specimens which in the compass of a single square inch, contain both varieties. Erom this fact as also from the exact similarity of position which they occupy in the mine, the differences in different varieties of coal are ascribed to original difference in the plants from which they were derived. Proceedings of Geological Society. Lond, and Edin. Phil. Mag. 3d Series, Vol. 2 p. 302. April

under publication by Professor Lindley and Mr. Hutton. The plants of the Bohemian Coal-field laid the foundation of Count Sternberg's Flore du monde primitif, the publication of which commenced at Leipsic and Prague in 1820.

Lindley and Hutton state (Fossil Flora, Vol. I. page 16) that "It is the beds of shale, or argillaceous schistus, which afford the most abundant supply of these curious relics of a former World; the fine particles of which they are composed having sealed up and retained in wonderful perfection, and beauty, the most delicate forms of the vegetable organic structure. Where shale forms the roof of the workable seams of coal, as it generally does, we have the most abundant display of fossils, and this, not perhaps arising so much from any peculiarity in these beds, as from their being more extensively known and examined than any others. The principal deposite is not in immediate contact with the coal, but about from twelve to twenty inches above it; and such is the immense profusion in this situation, that they are not unfrequently the cause of very serious accidents, by breaking the adhesion of the shale bed, and causing it to separate and fall, when by the operation of the miner the coal which supported it is removed. After an extensive fall of this kind has taken place, it is a curious sight to see the roof of the mine covered with these vegetable forms, some of them of great beauty and delicacy; and the observer cannot fail to be struck with the extraordinary confusion, and the numerous marks of strong mechanical action exhibited by their broken and disjointed remains."

A similar abundance of distinctly preserved vegetable remains, occurs throughout the other Coal fields of Great Britain. But the finest example I have ever witnessed, is that of the coal mines of Bohemia just mentioned. The most elaborate imitations of living foliage upon the painted ceilings of Italian palaces, bear no comparison with the beauteous profusion of extinct vegetable forms, with which the galleries of these instructive coal-mines are overhung.

The roof is covered as with a canopy of gorgeous tapestry, enriched with festoons of most graceful foliage, flung in wild, irregular profusion over every portion of its surface. The effect is heightened by the contrast of the coal-black colour of these vegetables, with the light ground-work of the rock to which they are attached. The spectator feels himself transported, as if by enchantment, into the forests of another world; he beholds Trees, of forms and characters now unknown upon the surface of the earth, presented to his senses almost in the beauty and vigour of their primeval life; their scaly stems, and bending branches, with their delicate apparatus of foliage, are all spread forth before him; little impaired by the lapse of countless Ages, and bearing faithful records of extinct systems of vegetation, which began and terminated in times of which these relics are the infallible Historians.

Such are the grand natural Herbaria wherein these most ancient remains of the vegetable kingdom are preserved, in a state of integrity, little short of their living perfection, under conditions of our Planet which exist no more.

SECTION II.

VEGETABLES IN STRATA ON THE TRANSITION SERIES.

*

THE remains of plants of the Transition period are most abundant in that newest portion of the deposites of this era, which constitutes the Coal Formation, and afford decisive evidence as to the condition of the vegetable kingdom at this early epoch in the history of Organic Life.

The Nature of our Evidence will be best illustrated, by selecting a few examples of the many genera of fossil plants

*See Pl. 1. Figs. 1, to 13.