J6 ERA OF THE CARBONIFEROUS FORMATION. 



of the cellular or cryptogamic kind, a proportion whic* 

 would probably be much increased if we knew the whoie 

 Flora of that era. The ascertained dicotyledons, or high- 

 er-class plants, are comparatively 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 which 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 coun- 

 tries, 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. f 

 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 Newcas- 

 tle, and of the torrid zone alike, are the fossil ferns arbore- 

 scent, showing clearly that, in that era, the present tro- 

 pical 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 cat- 

 kin 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 stems 

 from six inches to a foot in thickness. Arborescent plants 

 of this family, like the arborescent ferns, now grow only 

 in tropical countries, and there being found in the coal 

 beds in all latitudes is consequently held as an additional 

 proof, that at this era a warm climate was extended much 

 t arther to the north than at present. It is to be remarked 

 that plants of this kind (forming two genera, the most 

 abundant of which is the calamites) are only lepresent- 

 ed on the present surface by plants of the same family : 



* The principal families aie named spenopteris neuropteris and 

 pecopteris. 



f A specimen from Bengal, in the staircase of the British Muse 

 urn, is forty-five feet high 



