445 8 The thickness of the coal and of the freestone varies considerably in different parts, and the numbers here given must be taken only as an approximation. The strata are frequently deranged by faults, several of which run from east to west. În their general arrangement the strata usually run nearly parallel to each other, although they have always a considerable angle of elevation, and uniformly dip towards the Clyde. A great fault occurs between Hamilton and Quarter, and none of the principal seams are wrought for some miles north of this spot, the coal-beds being sunk nearly 100 fathoms lower than those out of the fault. The main seam worked at Quarter is 5 feet 6 inches thick, and consists of four distinct varieties of coal. This Coal-Basin of the Clyde extends into Renfrew, where there are many collieries. Coal is wrought in the parish of Eastwood, in that county, in several seams of various thickness, but none exceed 2 feet 6 inches. The whole are of good quality. Five of them are wrought in pits varying in depth from 10 to 40 fathoms. The coal-measures here consist of the usual series of freestone, shale, &c., dipping generally to the south-west. This coal formation partly surrounds the Loch of Castle Semple, and continues without interruption into Ayrshire, around Kilbirnie Loch, and onwards to Ardrossan. Coal occurs in different places in Dumbarton, where, among other parishes, it is wrought in Easter Kilpatrick. It is also found abundantly in Stirlingshire, along the southern base of the Lennox Hills. Čoal likewise occurs throughout Linlithgow, and is worked extensively in that county; it is likewise found in Clackmannan and in the south of the counties of Perth and Kinross. Some of the richest and most valuable bands of ironstone are obtained from the coal-measures of Scotland, chiefly in the basin of the Clyde. The manufacture of iron in this district is very extensive. In the year 1849 nearly 700,000 tons of pig-iron were wrought in this district. The Scotch beds include a large proportion of sandstone and a peculiar limestone, worked at Burdie House near Edinburgh. The remains of plants and animals are found in these rocks, and amongst the latter the Megalichthys, a fossil fish of large size and interesting structure. [MEGALICHTHYS.] Irish Coal-Fields.-Mr. Griffiths, in his Report on the Leinster Coal District,' gives an excellent summary of the Irish coal-fields, from which what follows is taken :-"If we except the Leinster district, my knowledge of the coal-fields of Ireland is as yet very limited; and though each in its turn will form the subject of a separate report, I think it right to draw attention to them in this place, by giving such general information as I possess respecting their situation and circumstances. Coal has been discovered in more or less quantity in seventeen counties of Ireland; but I believe the island contains but four principal coal-districts-namely, the Leinster, the Munster, the Connaught, and the Ulster. The two former contain carbonaceous or stone-coal, and the latter bituminous or blazing coal. "The Leinster coal-district is situated in the counties of Kilkenny, Queen's County, and county of Carlow. It also extends a short distance into the county of Tipperary, as far as Killenaule. This is the principal carbonaceous coal-district. It is divided into three detached parts, separated from each other by a secondary limestone country, which not only envelops, but in continuation passes under the whole of the coal-district; a fact which was indisputably, though accidentally, proved by the Grand Canal Company, who sank a pit through 18 yards of black slate-clay and flinty slate into the limestone in search of coal. The Leinster coal-district is therefore of subsequent formation to the limestone. "The Munster coal-district occupies a considerable portion of the counties of Limerick and Kerry, and a large part of the county of Cork. It is by much the most extensive in Ireland; but as yet there is not sufficient information respecting the number, extent, or thickness of the beds of coal it may contain. "Coal and culm have been raised for near a century in the neighbourhood of Kanturk, in the county of Cork. At Dromagh colliery I understand the work has been carried on to a very considerable extent, and its annual supplies of coal and culm have materially contributed to the agricultural improvement of an immense extent of the great maritime and commercial counties of Cork and Limerick, which must otherwise have continued neglected and unreclaimed. "Many circumstances combine to make the examination of this district of peculiar interest and importance; and as a recent application has been made by the Cork Institution to the Dublin Society to aid the undertaking, it is probable that this immense district will shortly be minutely explored. From all that has been ascertained, it is very clear that the dip of the beds and the quality of the coal differ materially from those of the Leinster district. In the Munster district the beds run east and west, and dip to the south, forming an angle of 45°. In the Dromagh colliery, where all the beds which "No work has been undertaken in the Munster coal-district to a greater depth than 80 yards. The present work at the Dromagh colliery is at that depth; it is heavily watered, and consequently expensively wrought. The quality of the coal and culm improves as the work descends. "The Connaught coal-district stands next in order of value and importance to the Leinster and Munster, and possibly may be found to deserve the first place when its subterranean treasures shall be explored. At present nothing is known, except that the outer edges of several beds of coal have been observed, but they have not been traced to any distance, so that their extent is by no means ascer tained. The coal is of the bituminous species. This coal is particularly adapted to the purposes of iron-works, foundries, &c. &c. "The Ulster coal-district is of trifling importance when compared with the foregoing. It commences near Dungannon, in the county of Tyrone, and extends in a northern direction to Coal Island, and in continuation to the neighbourhood of Cookstown. No beds of coal worth working have hitherto been discovered between Coal Island and Cookstown, but certainly the coal strata extend there. The principal collieries are at Coal Island and at Dungannon. The coal of this district is bituminous. I understand that indications of coal have been observed at Drumquin, in the county of Tyrone; and also at Petigoe, to the north of Lough Erne. Possibly the coal formation may extend from the neighbourhood of Cookstown westward to the north of Lough Erne. "Besides the foregoing principal coal-districts, there are others of less consequence. Bituminous coal has been found in the neighbourhood of Belturbet, in the county of Cavan, and at the collieries of Ballycastle, in the county of Antrim; but the Antrim coal-district is not very extensive. These collieries have been wrought for a number of years. The coals are of a slaty nature, and greatly resemble both the coal and the accompanying rocks which occur in Ayrshire, and probably they belong to the same formation." Continental Europe.-France.-In the centre and south of France some small coal-fields occur in the valleys of the Loire, the Allier, the Creuse, and the Dordogne, the Aveyron, and Ardèche, between ridges proceeding from the primitive central group connected with the Cevennes; and, in a few localities, some of the thickest beds of coal yet discovered have been found. In the north of France, the coal-formation occupies a very large tract of country, running westward from Hardinghen, near Boulogne, by Valenciennes, and thence up the Schelde and down the Meuse to Eschweiler, beyond Aix-la-Chapelle. The total area of coal in France is probably not less than 2000 square miles. Its annual yield is not less than 4,000,000 tons. These deposits are of the same age as those of England, but they rest on granite or other crystalline and metamorphine rocks. Belgium.-The district along the Meuse, between Namur and Liège, is said to resemble in its geological structure, as well as picturesque features, the Somersetshire and South Gloucester district : the strata being broken and deranged, exhibit, if possible, still more contorted and inverted positions of the respective beds. The defiles of the Sambre and the Meuse (Geol. Trans.,' vol. i., 2nd series) present an exact counterpart of those of the Avon and the Wye. There are two principal coal-fields in Belgium, the one extending to the east and known as the Liège Coal-Field, and the other west forming the Hainault division. The seams are generally thin, remarkably numerous, and presenting an apparent multiplication by doublings of the strata. A kind of coal is found in Belgium called Flenu Coal, which is not found in Great Britain. It burns rapidly, giving out a disagreeable smell. [BELGIUM, in GEOG. DIV.] Germany. The coal-districts in the north of Germany are probably the prolongation of the Belgium formation. On the north-east and south-east of the Harz Mountains, near Ballenstadt and Neustadt, the coal-formation occurs resting on the transition rock of that group. In Saxony coal is found in many places along the northern foot of the Erzegebirge. It is extensively worked near Zwickau and near Dresden. There is a very extensive coal-district in Bohemia, extending into Upper Silesia. This district lies between the great primitive chain of the Erzegebirge and the Riesengebirge, on the north, and the great district of primitive slate which occupies the larger part of Sweden.-Coal occurs in this country near Helsingborg at the entrance of the Baltic, and also in the island of Bornholm. [BORNHOLM, in GEOG. DIV.] Spain. Both bituminous coal and anthracite are found in Spain. The richest beds are in Asturias, where the measures are so much broken and altered as to be worked by almost vertical shafts driven through the beds. The area covered by coal-beds in Spain is not exactly known, but it is said to be the largest in Europe, presenting upwards of 100 workable seams varying from 3 to 12 feet in thickness. (Ansted.) Hungary and some other countries in the east of Europe contain coal-measures which appear to belong to the carboniferous period. It has been conjectured that coal exists in several parts of continental Greece. Coal is said to be found north of Constantinople. Asia.-In Asia coal has long been known in China, where it is said to have been worked as early as the 13th century. Mr. Williams says that both bituminous coal and anthracite are seen in the coal marts of the north of China. Coal is likewise found in the countries immediately around the Persian Gulf, but of a very indifferent description. In most parts of Cutch, coal occurs in abundance and of good quality; it ignites quickly, and burns to a white ash. Coals are also found in Bundelcund. There are large mines in the district of Burdwan, 130 miles from Calcutta, and worked to the extent of 14,000 or 15,000 tons annually. They are situated on the banks of a river connected with the Hoogly, and were first worked about thirty-five years ago, but they have not been in extensive operation more than twenty-five years; the principal seam is about 9 feet thick, and is about 90 feet from the surface. Coal has likewise been got from a mine opened near Bhaugulpoor, on the Ganges, about 300 miles from Burdwan. Another coal-field has been discovered on the banks of the Hoogly, near Merzipoor, about forty miles from Calcutta; the coal is found close to the surface, and the thickness of the principal seam is said to be 2 feet. Coal of good quality likewise occurs in the Birman Empire. America.-Professor Ansted says, "It is only within a few years that the coal-measures of the continents of America have been in any way known, and we are even now in ignorance of many details with regard to the greater number; but enough is ascertained to convince any unprejudiced person that the supply of mineral fuel there obtainable is amply sufficient for the requirements of the whole civilised world for thousands of years, even should the demand increase rapidly and the consumption continue to bear reference to the multiplication of all kinds of industrial occupation. There are in North America four principal coal areas, compared with which the richest deposits of other countries are comparatively insignificant. These are the great central Coal-Fields of the Alleghanies; the Coal-Field of Illinois and the basin of the Ohio; that of the basin of the Missouri; and those of Nova Scotia, New Brunswick, and Cape Breton. Besides these there are many smaller coal areas which in other countries might well take rank as of vast national importance, and which even in North America will one day contribute greatly to the riches of various states. We will endeavour to give a brief outline of the main facts concerning the chief of these districts. "The Alleghany or Appalachian Coal-Field measures 750 miles in length, with a mean breadth of 85 miles, and traverses eight of the principal states in the American Union. Its whole area is estimated at not less than 65,000 square miles, or upwards of 40,000,000 of acres. The area is thus distributed "Making a liberal deduction for unproductive portions, denuded and eroded strata, and the parts of the seams out of reach, we may still fairly calculate that there exists in this district an area of 25,000,000 The working has already comacres of productive coal-measures. menced in most of the states above mentioned, though not generally to any very considerable extent. Thus in Alabama, the beds alternate "British America contains very large supplies of coal in the provinces Nova Scotia contains a great quantity of coal. The great coal-field of Pictou has been traced from Carriboo Harbour to Merigomish, comprising an area of more than 100 square miles. The seams of coal resemble much more those of Staffordshire than those in the north of England. One bed is described by a practical miner, who went to Nova Scotia to superintend the opening of the mines, as 40 feet in thickness; it is not however equally good throughout, and it was thought advisable to work only 10 feet of the upper part. According to Bouchette, the seams of this field vary in thickness from 1 foot to 50 feet. The coal is highly bituminous and burns well. There is another coal-field, also of considerable extent, in the northwest part of the county of Northumberland, between the river Macan and the shores of the Chignecti Channel. In this district there are eight strata of coal, varying from 1 foot to 4 feet in thickness. This coal is not considered so good as that of Pictou. There are also indications of coal in the township of Londonderry and at Onslow; on the north shore of the Mina's basin; at the head of Pomket Harbour, in the upper district of the county of Sydney; and on the south shore of Wallace Harbour, in the county of Cumberland. (Bouchette.) The coalCoals of excellent quality are got in Cape Breton. measures have been traced in the western part of the island, on Inhabitants River, at Port Hood, and at Mabou. On the east the Sydney Coal-Field is of great extent; it commences at Miray Bay and runs along the coast to the Great Bras d'Or, being in length about 40 "From a minute calculamiles, and averaging 5 miles in breadth. tion, after deducting harbours, bays, and all other interpositions, it appears that there are 120 square miles of land, containing available veins of coal." (Bouchette.) The measures in this district contain fourteen beds of coal, varying from 3 to 11 feet in thickness. The coal is wrought at Sydney Harbour and at Lingan. Coal is found very abundantly in Australia, and is worked extenA coal sively in the Newcastle district, on the Hunter's River. formation likewise occurs in Van Diemen's Land; and coal has been found and is wrought in several parts of New Zealand. [Supp.] 96 Sedgwickia. Solemya primava Solen pelagicus Atocrinus Milleri Cyathocrinus . Venus Echinocrinus 5 Ungulina antiqua CONCHIFERA MONOMYARIA. Anomia antiqua Avicula 16 Gervillia. 5 Lima 662 524 Inoceramus Meleagrina Monotis æqualis Posidonomya Pterinea Atrypa BRACHIOPODA. 2 Crania vesiculosa Leptana Lingula Orbicula. Orthis 2 Productus 4 Terebratula 17 A croculia 3 Buccinum Cirrus In general the impressions of plants occur chiefly in the shale of the coal-measures, that is, in the mud which separates the seams of 3 coal, or in the sandstone or ironstone associated with the coal formation; and as such impressions are much more distinct than any that occur in the coal itself, it is chiefly from them that our ideas of the vegetation from which coal has been produced have been derived. 16 They are often present in inconceivable beauty and abundance, as 4 may be imagined from Dr. Buckland's graphic account of those in the coal-mines of Bohemia. In his 'Bridgewater Treatise,' he says: 7 6 8 "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 75 9 the galleries of these instructive coal mines are overhung. The roof 3 is covered as with a canopy of gorgeous tapestry, enriched with 9 5 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 4 unknown upon the surface of the earth, presented to his senses 5 almost in the beauty and vigour of their primeval life; their scaly 12 17 4 stems and bending branches, with their delicate apparatus of foliage, are all spread forth before him, little impaired by the lapse of 46 countless ages, and bearing faithful records of extinct systems of 59 vegetation, which began and terminated in times of which these relics are the infallible historians." 26 GASTEROPODA. 4 5 Such remains consist chiefly of impressions of leaves separated from their branches, and of casts of trunks more or less in a broken state; and with them occur now and then pieces of wood or remains 8 of trees in which the vegetable texture is to some extent preserved. Of the leaves the greater part is more or less mutilated; those of ferns, which are extremely numerous, have lost their fructification in 2 the majority of instances; and it frequently happens that the 17 leaflets of compound leaves have been disarticulated either wholly or partially. Stems or trunks are in all cases in a state which must 3 be supposed to result from decay previously to their conversion into coal; destitute of bark, or with the principal part of that envelope 11 gone, and often pressed quite flat, so that all trace of their original convexity is destroyed. Where ripe fruits are met with, they are not 5 in clusters as they probably were when alive, but separated into single individuals. Of flowers there is no trace that can be satisfactorily identified; for Antholithes Pitcairnia, the most perfect that has yet been discovered, is altogether of a doubtful nature. It will at once be seen that the investigation of plants in such a condition is very much more difficult than that which is presented by a recent Flora, The nature of the inquiries, and the difficulties presented to an investigator of the plants of the coal formation, have been well described by Dr. Joseph D. Hooker, in a paper On the Vegetation of the Carboniferous Period as compared with that of the Present Day,' in the second volume of the 'Memoirs of the Geological Survey of Great Britain.' His remarks are arranged under four heads the nature of the plants, their geographical distribution, relation to the soil, and the reciprocal influence of the whole mass of the vegetation on the surface it covers : "1. Of the mutual affinities of the groups under which the majority of the genera of coal-plants arrange themselves little more can be said but that the ferns occupy the lower end of the series and the Conifera possibly the highest; but this depends upon the view taken of the affinities of Sigillaria, the most important group. These are classed by some observers amongst Ferns, by others with Conifera, another considers them as linking these two widely different families, whilst a fourth ranks them much higher than either. The affinities of another group, Calamites, are entirely unascertained. Of the whole amount of species in each no conjecture can be formed, or any but a very rough one, of the number into which those with which we are familiar as of common occurrence should be divided. The Ferns far outnumber probably all the others; but this again materially depends on the value according to the markings of Sigillaria, as means of dividing that genus; for if the slight differences hitherto employed be insisted upon, the number of the so-called species may be unlimitedly increased. "2. With regard to the geographical distribution of the species, &c., it appears that a uniformity once existed in the vegetation throughout the extra-tropical countries of the Northern Hemisphere, to which there is now no parallel; and this was so whether we consider the coal-plants as representing all the flora of the period, or a part only, consisting of some widely-distributed forms that characterised certain local conditions. Nor is this uniformity less conspicuous in what may be called the vertical distribution; the fossils in the lowest coal-beds of one field very frequently pervading all the succeeding beds, though so many as thirty may be interposed between the highest and the lowest. "3. Of the relations between the soil and the plants nourished by it, little more is recognisable than that the Sigillaria have been particularly abundant on the under clay, which, judging from the absence of any other fossils but Sigillaria roots (Stigmaria), seems to have been either in itself unfriendly to vegetation, or so placed (perhaps from being submerged) as to be incapable of supporting any other. The latter is the most probable, because both Sigillaria and their Stigmaria roots occur in other soils, besides under clay, and are there accompanied by Calamites, Ferns, &c. The Conifera again are chiefly found in the sandstones, and their remains being exceedingly rare in the clays, shales, or ironstones, it may be concluded that they never were associated with the Sigillaric and other plants which abound in the coal-seams, but that they flourished in the neighbourhood, and were at times transported to these localities. The quantity of moisture to which these plants were subjected must remain a question so long as some authors insist upon the Sigillarice being allied to plants now characteristic of deserts, and others to such as are the inhabitants of moist and insular climates. The singular succulent texture and extraordinary size of both the vascular and cellular tissues of many, possibly indicate a great amount of humidity. The question of light and heat involves a yet more important question, some of the coal-plants of the arctic regions being considered identical with those of Britain. How these can have existed in that latitude under the now prevailing distribution of light and heat has not been hitherto explained; they are too bulky for comparison with any vegetables inhabiting those regions at the present time, and of too lax a tissue to admit of a prolonged withdrawal of the stimulus of light, or of their being subjected to continued frosts. 4. The consequence of the existence of the coal-plants has been the formation of coal; but how this operation was conducted is a question yet unsolved. The under-clay or soil upon which the coal rests, and upon which some of the plants grew, seems in general to have suffered little change thereby, further than what was effected by the intrusion of a vast number of roots throughout the mass. The shales on the other hand are composed of inorganic matter, materially altered by the presence of the vegetable matter they contain. The iron-clays again present a third modification of this mixture of organic and inorganic matter, often occurring in the form of nodules. These nodules seem to be the result of a peculiar action of vegetable matter upon water, charged with soil and a salt of iron; the ironstone nodules of existing peat-bogs appearing altogether analogous to those of the carboniferous period, whether in form or in chemical constituents. Here then the botanist recognises in one coalseam a vegetable detritus under three distinct phases, and which has been acted upon in each by very different causes. In the underclay there are roots only; these permeate its mass as those of the water-lily and other aquatic plants do the silt at the bottom of still waters. These "The coal is the detritus either of those plants whose roots are preserved in the under-clay, or of those together with others which may have grown amongst them or at a distance, and have been afterwards drifted to the same position. Above the coal is the third soil, bearing evidence of the action of a vigorous vegetation; this is the shale, which has all the appearance of a quiet deposit from water charged with mineral matters, and into which broken pieces of plants have fallen. Here there is so clear a divisional line between the coal and shale that it is still a disputed point whether the plants contained in the latter actually grew upon the former, or were drifted to that position in the fluid which deposited the mineral matter. Amongst the shales are also interspersed in many cases innumerable stumps of Sigillaria, similar to those whose roots occur in the under-clay, and which are themselves found attached to those roots in soils similar to the under-clays, but unconnected with any seam of coal. stumps are almost universally erect, are uniformly scattered over the seams, and otherwise appear to have decidedly grown on the surface of the coal; the shales likewise seem deposited between these stumps. The rarity of Sigillaria roots (Stigmaria) in this position is probably due to their being incorporated with the coal itself, though they sometimes occur above that mineral and between the layers of shale. The seams of ironstone (or black band) are the last modifications of soil by vegetable matter to which allusion has been made. When these are uniform beds or layers, they may be supposed to be the deposit from water charged with iron and soil which has percolated through the peat, and in so doing absorbed a great deal of vegetable matter. The layers of nodular ironstone are simple modifications of these, and may be caused by the sedimentary particles contained in the fluid, which instead of being deposited in a uniform stratum, are aggregated round bits of vegetable matter (as fern leaves, stems, or cones) which served as nuclei. "Now, though each of these points admits of some explanation when taken separately, and some illustration from the action of an existing vegetation on the soil, &c., it is very difficult to understand their combined operation over so enormous a surface-for instance, as one of the American coal-fields-and even more to account for their regular recurrence according to some fixed law in every successive coal-seam throughout the whole carboniferous formation." Coal-plants may be divided for practical purposes into three classes : 1, those of which only wood still containing organic structure has been found; 2, those which have an obvious analogy with recent plants; 3, those with which no existing analogy has been traced. 1. Coal-Plants of which Wood only containing Organic Structure has been found. The existence of wood in the coal formation with its texture still preserved, is a discovery of very modern date. Mr. Nicol, of Edinfossil wood so as to show its structure microscopically; Mr. Witham burgh, claims the credit of having first invented the art of preparing has investigated the subject extensively, and he has been followed by Messrs. Lindley, Hutton, and others. The result of these inquiries has been, that wood still preserving its texture exists in a mineral state extensively throughout the coal-mines of the north of England; that it in most cases has a structure analogous to, although not identical with, that of recent coniferous wood; and that in those cases in which its structure is not coniferous it is unlike that of any existing trees. small discs upon the sides of its woody tubes; differences in the Coniferous wood is known amongst other things by the presence of arrangements of these discs have given rise to the formation of the genera Peuce and Pinites, to one or other of which all the coniferous coal-wood seems referrible. Mr. Nicol believes that it may all be referred to either the existing genera Pinus or Araucaria. Specimens of this kind of wood occur sometimes of considerable size. A trunk of Pinites Brandlingi has been found 72 feet long, and another of Pinites Withami 36 feet long. The wood to which Mr. Witham's genus Anabathra apparently belongs is known by its longitudinal section representing tubes marked by parallel transverse lines resembling the steps of a ladder. This is very uncommon, and is stated by Messrs. Lindley and Hutton to belong to the genus Stigmaria, mentioned hereafter. Specimens in ironstone also have occurred of the wood of the genus Lepidodendron. It consists principally of loose cellular tissue, bases of the leaves by arcs of spiral vessels, and having rudiments of having near the centre a zone of spiral vessels, connected with the wood on the outside of the zone. 2. Coal-Plants which have an obvious Analogy with Recent Plants. Coniferous plants have but few remains, except wood, by which they can be recognised. A cone of Pinus anthracina has been met with, and there is reason to believe that certain stems called Bothrodendron, having numerous minute dots upon their surface, and deep circular oblique concavities 4 or 5 inches across, at intervals of 10 or 11 inches, are also remains of trees of this description. It is probable moreover that some of the fossils referred to the genus Lepidodendron are really coniferous plants, especially L. longifolium; but upon this point nothing certain is known. It was at one time supposed that the remains of palms had been found the evidence, however, upon which this supposition rests is considered by M. Brongniart and Dr. Hooker as insufficient. The only portions of plants supposed to be palms that have been found, are the remains of fruits. These remains are generally oblong 3-sided or 6-sided bodies, not more than an inch long. They have been named Trigonocarpum Nöggerathi. Trigonocarpum Nöggerathi. Lycopodiaceous plants, or what are considered analogous to them, form a very large proportion of the vegetable remains of the north of England coal-field. They are represented by impressions closely covered either with lozenge-shaped spaces disposed in a spiral manner, or by small scale-like leaves, which are supposed to have produced those spaces by falling off. When they branch they have often been observed to do so in a forked or dichotomous manner. Sometimes they are minute, and no larger than existing Lycopodia, but they are occasionally found of considerable size, some having been seen which, although mere fragments, were between 40 and 50 feet long, and more than 4 feet in diameter. An idea of their appearance will be gained from the accompanying figure of Lepidodendron Sternbergii. admits that with regard to the small species of Lepidodendron, it is more probable that they belonged to the genus Lycopodium; but there is nothing remarkable in their stature. Ferns are the most abundant of all plants in the shale of the coal, almost every yard of it being more or less marked by their impressions, and very often containing them in great multitudes. It has been estimated that of the vegetable remains belonging to the Coal Flora, one-half at least of the species are ferns. They are in most cases destitute of fructification, so that they cannot be arranged according to the system in use for recent species; and consequently M. Adolphe Brongniart, the great writer upon these subjects, has divided them into genera characterised chiefly by the way in which the veins are disposed. The number of ferns renders it convenient that some such classification should be formed, and M. Brongniart's plan has been adopted by all other writers. It is no part of our object to go into such details in this place, but it will be useful to many of our readers to know what the differences are between some of the most common of these fossil genera. Such are the following: Pecopteris consists of species whose leaves are once, twice, or thrice pinnated, with the leaflets either adhering by the whole breadth of their base, or by the centre only. The midrib runs quite through to the point, and the veins are planted upon it somewhat perpendicularly. Associated with them are narrow sharp-pointed leaves resembling scales, which no doubt belonged to them, but which are distinguished by the name of Lepidophyllum. In the same formations are found cones of different sizes, consisting of small sharp-pointed lax scales, in the axils of which were seeds: these have been supposed to be the fructification of Lepidodendron; but as there is no actual certainty of the fact, they bear the name of Lepidostrobi. The above figure represents Lepidostrobus variabilis. [LEPIDOSTROBUS.] Lepidodendra are usually quoted as an instance of ancient species belonging to the same genus as modern plants of very humble stature (for existing Lycopodia, although they acquire sometimes the length or height of three or four feet, are always more like mosses than trees), having arrived at gigantic dimensions in the remote ages when coal was deposited. This is the opinion of M. Adolphe Brongniart and Dr. Joseph Hooker, who have both studied this subject carefully. Dr. Lindley has however expressed the opinion that the Lepidodendra are allied to the Coniferæ. He argues, in the first place, that there is no certainty whatever that the most gigantic Lepidodendra were not fir-trees, analogous to Araucaria; a conjecture which is rendered the more probable by Mr. Nicol's discovery that some of the specimens of fossil coniferous wood are nearly identical with the wood of that genus. Now, the Norfolk Island Pine, which is a species of Araucaria, is one of the largest of known trees. In the second place, it is asserted that Lepidodendron Harcourtii is not a Lycopodiaceous plant at all, but an extinct genus, intermediate in organisation between Conifera and Lycopodiacæ, connecting Gymnosperms and Acrogens more directly and satisfactorily than any known plant. Dr. Lindley |