in the distribution of land and water-shallower seas-larger rivers and estuaries-wide, far-stretching swampy lands; andwith these, new ocean-currents, a more genial and equable climate, and, as a concomitant, a more exuberant exhibition, and over wider areas, of vegetable and animal life. In some regions, but by no means over the whole world, the transition from the one period to the other seems to have taken place through convulsive energy; and hence in these regions comparatively few of the forms of the old red sandstone survive, or pass into the carboniferous era. As in every other period, the new forms come slowly and gradually on the stage, attain their "culminating point," or period of greatest variety, size, and numbers, and then gradually or quickly decline, according to the continuity of the conditions by which they are surrounded. In the vegetable world we have now a most exuberant Flora-so exuberant that it is but faintly paralleled by the rankest growth of the tropical jungle. To account for this extraordinary development of plant-life, over such wide and diversely situated regions of the globe, various hypotheses have been offered, such as a larger percentage of carbonic acid gas in the atmosphere-the greater effect of the earth's central heat-change in the earth's axis of rotation, so as to bring the coal-bearing areas within the tropics-and greater eccentricity of the earth's orbit, so as to have brought the globe periodically nearer to the sun's influence; but as we have not in the mean time* a shadow of proof for such abnormal causes, and much evidence to the contrary, we are bound by sound induction to seek for the explanation in *We say in the mean time; for the recurrence of colder and warmer cycles over the northern hemisphere, as evinced by the geological record, is clearly the result of some great cosmical law, depending either on telluric or on solar influences, and, as such, must sooner or later be satisfactorily determined.-See Concluding Chapter-"The Law," Section 6. the then peculiar distribution of sea and land, in the altitude of its shores, in the arrangement of warmer aërial and oceanic currents, and generally in a concentration of these conditions, such as would produce the necessary climate. And, after all-as in the case of the great tertiary elephants and rhinoceroses of Northern Europe, whose representatives are now found only in the tropics-we know too little of the nature of the plants to say under what conditions of climate they would attain their greatest exuberance, though we clearly perceive from their foliage and mode of growth that it was at once equable and continuous.* Generally speaking, we find them resembling equisetums, marshgrasses, reeds, club-mosses, tree-ferns, and coniferous trees; and these in existing nature attain their maximum development in warm-temperate and subtropical, rather than in equatorial regions. The Wellingtonias of California, and the pines of Norfolk Island, are more gigantic than the largest coniferous tree yet discovered in the coal-measures; the tree-ferns of New Zealand luxuriate in humid and shady spots; the tussack of Falkland Island, and the phormium of New Zealand, show leaves as broad and long as the poacites of the carboniferous period; while accumulations of peat-growth are the products of coldly-temperate, rather than of equatorial latitudes. Besides all this, we have coal-beds in other formations-the oolite, the Wealden, and tertiary; and if we are to go in search of abnormal conditions for the production of the one, we must admit the existence of similar causes for the production of the other— an admission, as we shall afterwards see, that would lead to * It is more than likely, as suggested by the late Robert Brown, that many of the Coal-plants were inhabitants of the swamp and shallow waters-estuarine and marine; and that, rooted in mud, rich in organic matters, and surrounded by water of an equable and genial temperature, they enjoyed the conditions at once of a rapid and of a gigantic growth. irreconcilable absurdities. product of every period, and is merely the mineralised result of vegetable accumulation-pointing rather to immensity of time than to rapidity of growth as the cause of that accumulation. It is to time, therefore, and to genial equability of climate, rather than to excessive temperature, that we are to look for an explanation of the vegetable masses of the coal period; and he who would cut short the difficulty by appeals to abnormal conditions, instead of exhausting the possibilities within the scope of natural law, at once does violence to Nature, and retards the progress of legitimate induction. The fact is, coal is a necessary The vegetation to which we allude consists of fucoids and confervites, or sea-weeds and confervæ; of equisetites, hippurites, and asterophyllites, gigantic plants resembling the horse-tails of our swamps and ditches; of innumerable treeferns distinguished by the forms and venation of their leaves, as neuropteris (nerve-fern), cyclopteris (circle-fern), glossopteris (tongue-fern), pecopteris (comb-fern), sphenopteris (wedge-fern), and the like; of fern stems, caulopteris; of reed-like plants, calamites; of palms,* palmacites and Noeggerathia; of a vast variety of trees of unknown relationship, as sigillaria (fluted bark), stigmaria (dotted bark), now known to be the roots of sigillaria, &c., lepidodendron (scaly stem), bothrodendron (pitted stem), favularia (honeycombed bark), and the like; and of true coniferous trunks * It has been recently questioned, and apparently on good grounds, whether we have certain evidence of the existence of palms during the Carboniferous epoch? The three-cornered fruits (trigonocarpum), formerly supposed to be those of palms, are now regarded as those of coniferous plants, which, like the berry of the juniper, was enclosed in a fleshy envelope; while the broad flabelliform or fan-shaped leaves (Noeggerathia) are also considered coniferous and akin to the existing subtropical Salisburia. The so-called palm-stems have always been held as doubtful. G resembling the pine, araucaria, peuce, yew, &c., and hence known as pinites, araucarites, peucites, and taxites. As RESTORED ASPECT OF CARBONIFEROUS FLORA. Calamite; Bothrodendron; Equisetites; Asterophyllites; Lepidodendron: Caulopteris, or Tree-fern; Sigillaria, with Stigmaria roots; Lycopodites: Pecopteris, &c. yet, we have only two or three doubtful instances of a dicoty ledonous flora-the majority of the preceding forms being monocotyledons and conifers. Occurring as they do in stony and carbonised fragments, their relations are but ill understood; and botanists have as yet contented themselves by pointing out resemblances rather than in establishing true affinities. Whatever their nature, they must have grown in vast luxuriance and variety, clothing every riverside and plain, and spreading over every swamp in one impenetrable jungle,—and this, season after season, and age after age, till their accumulated growth completed the coalbeds now so indispensable to the progress of civilisation. It is customary for a certain class of writers to descant on the "dreary and flowerless monotony" of the vegetation of the Coal period. This, however, is an error. Though all the equisetums and club-mosses and ferns were undoubtedly flowerless, the higher gymnogens and endogens were not so, as we have evidence in the fossil flowers and fruits (antholites and carpolites), which thickly stud many of the shales; and we have often thought that what was wanting in blossom was more than compensated for by the profusion of light symmetrical, feathery fronds, and by the tall pillar-like stems which rose, each one boldly carved with its own peculiar pattern. The trunks of a modern forest are rough and gnarled; those of the period now under review sprang up like the sculptured shafts of a medieval temple, graceful in proportion, and rich in ornament through the endless repetition of flutings, spirals, zigzags, lozenges, ovals, and other geometrical designs-these designs being the persistent leaf-scars of a vegetation simpler in structure and more primitive in plan. When we turn to the Animal Life of the period, which belongs almost exclusively to the waters, we find it equally exuberant in numbers and in variety. Life abounds near shore and in the shallow waters-life is rife in the deeper |