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Show 46 ERA OF THE CARBONIFEROUS FORM~!.TION. of the cellular or cryptogamic kind, a proportion which would probably be much increased if we knew the whole Flora of that era. The ascertained dicotyledons, or higher- class plants, are cornparatively few in this formation; but it will be found that they constantly increased as the globe grew older. The master-form or type of the era was the fern, or breckan, of'" hich about one hundred and thirty species have already been ascertained as entering into the com position of coal.* The fern is a plant which thrives best In warm, shaded, and moist situations. In tropical countries, where these conditions abound, there are many more species than in temperate climes, and some of these are arborescent, or of a tree-like size and luxuriance. t The ferns of the coal strata have been of this magnitude, and that without regard to the parts of the earth where they are found. In the coal of Baffin's Bay, of Newcastle, and of the torrid zone alike, are the fossil ferns arborescent, showing clearly that, in that era, the present tropical temperature, or one even higher, existed in very high latitudes In the swamps and ditches of England there grows a plant called the horse-tail,( equisetum,) having a succulent, erect, jointed stem, with slender leaves, and a scaly catkin at the top. A second large section of the plants of the carboniferous era were of this kind, (equisetacete,) but, .like the fern, reaching the magnitudes of trees. While existing equiseta rarely exceed three feet in height, and the stems are generally under half an inch in diameter, their kindred, entombed in the coal beds, seem to have been generally fourteen or fifteen feet high, with sterns from six inches to a foot in thickness. Arborescent plants of this family, like the arborescent ferns, now gro\v only in tropical countries,. and there being found in th~. coal beds in all latitudes Is consequently held as an additional proof, that at this era a warm climat~ w_as extended much farther to the north than at present. It Is to be remarked that plants of tbis kind (forming two genera, the most abundant of which is the calamites) are only represented on the present surface by plants of the same. fantily: • The principal f<.11nilies axe named spenopteris neuropteris and pecopteris. . . t A specimen from Bengal, in the staircase of the BntJsh Muse llm, is forty-five feet high. COMMENCEMENT OF LAND PLANTS. 41 thP. ttpecV:s which flourished at this era gradually lessen in number as we advance upwards in the series of rock9, and disappear before we arrive at the tertiary formation. The club-moss family (lt copodiacetE) are other plauts of the present surface, usu~ Hy seen in a lowly. and creepina- form in temperate lahtudes, but presenting spec1es which rise to a, greater magnitude within the trovics. lviany specimens of this family are found in the coal beds; it is thouO'ht they have contributed more to the substance of the coal than any other family. But, like the ferns and equisetacere, they rise to a prodigious magnitude. The iepidodendra (so the fossi~ genus is c_alled)_ have pr~bably been from sixty-five to eighty feet 1n hmght, h_avrng at their base a dian1eter of about three feet, wlule their leaves measured twenty inches in length. In the forests of the coal era, the lepidodendra would enjoy the rank of firs in our forests, affording shade to the only less stately ferns and calamites. The internal structure of the stem, and the character of the seed-vessels, show them to have been a link between single-lobed and donble-lobed plants, a fact worthy of note, as it favors the idea that, in vegetable as well as animal creation, a progress has been observed, in conformity ·with advancing conditions. It i~ also curious to find a missing link of so much importa~ce in a genus of plants which has long ceaS1ed to have a living place upon earth. The other leading plants of the coal era ar~ without representatives on the present surface, and their characters are in general less clearly ascertained. Amongst the most remarkable are-the sigillaria, of which large stems are very abundant, showing that the interior h~s been Boft, and the e:lCterior fluted with separate leaves Inserted in vertical rows along the flutings-and the stigmaria plants apparen'tly calculated to flourish in marshes OJ po0ls, having a short, thick, fleshy stem, with a domeshaped top, from which sprung branches of from twentJ· to thirty feet long. Amongst monocotyled~ns were some palms, (jlabellaria and ntEggerathiu,) besides a few n0f distinctly assignable to any class. . The dicotyledons of the coal are comparatively fevy, though on the present surface they are the .most numer~u~ sub-class. Besides some of doubtful affinity (annztlana: usterophyllites, &c.) there were a few of the pine family. .vhich seem to have been the highest class, of trees oJ |