o 



148 THE CARBONIFEROUS SYSTEM. 



been recognised by Lesquereux, who has also marked out a number 

 of interesting parallelisms in the beds of the Middle Coal formation. 

 In Illinois and Iowa, the Lower Carboniferous marine limestones 

 present several important subdivisions, and still farther west there 

 appear to be Upper Carboniferous marine beds graduating upward 

 into Permian. 



In England the Mountain Limestone, the Millstone-grit, and the 

 Coal Formation, have been the members usually recognised, but 

 recently attention has been attracted to the Lower Coal measures, 

 which are also developed there; and in 1865, I saw in the Museum 

 of the Geological Survey a small collection of undetermined plants 

 from these beds, perfectly corresponding to those of the Lower Coal 

 formation of Nova Scotia. The tei'm Lower Coal measures is, how- 

 ever, in England and Scotland, usually applied to beds corresponding 

 to the lower part of the Middle Coal formation of the above classifi- 

 cation. With regard to the Upper Coal formation, its equivalent is 

 recognised in the English and Scottish coal-fields as the overlying 

 barren coal measures, either destitute of coal or with thin and un- 

 workable seams, and which in the Lancashire Coal-field amount to 

 nearly 2000 feet in thickness. In Lancashire these beds are very 

 similar to the corresponding series in Nova Scotia. In the Scottish 

 coal-fields they contain marine limestones, — a circumstance which 

 occurs in one instance in Nova Scotia. Much remains to be done in 

 Great Britain for the proper working out of the distinction in the 

 flora of the members of the Carboniferous system, the study of fossil 

 plants of the coal having been much neglected by geologists. 



In Germany, where the subject of the coal flora has received 

 greater attention, the subdivisions have been more fully worked out ; 

 and I have much pleasure in quoting the following remarks by 

 Professor Geinitz of Dresden, from a review of my paper on the " Con- 

 ditions of Accumulation of Coal," in the "Isis," 1866 : — 



u In comparing the distribution of this flora with that in the various 

 zones of the Carboniferous of Europe, it is first of all a surprising 

 fact, that there also the zone of the Lower Coal formation must be de- 

 signated, as in Europe, the Lycopodiaceous zone, since Lepidodendron 

 corrugatum is the most remarkable and predominant plant in it. But 

 this species approaches so closely the Lycopodites polyphyllus, Rom. 

 sp. (Geinitz, Flora of the Hainichen, Ebersdorf Basin), that both of 

 them might be considered as identical, whilst Lep. tetragonum St. 

 (Gein., etc.), and Knorria imbricata St. (Gein., etc.), which we must 

 still continue to regard as an independent plant, are likewise quite 

 characteristic of the oldest Coal formation or culm of Europe. The 



