237 



Araucarice. Some species of this kind still exist in the flora of onr time, 

 inhabiting the sonthern part of the American continent, and the south- 

 ern islands, Isew Holland and New Caledonia. The presence of these 

 Conifers in the Devonian of North America is remarkable for two 

 reasons : first, because they enter the land flora about the same time 

 as the Lycopodiaceous species; and, secondly, because as yet no remains 

 positively referable to trunks of Conifers have been recognized in the 

 Carboniferous formation of the United States, though species of the 

 same relation are described from the Subcarboniferous measures of 

 Canada and of England.* 



A few of the species of ferns of the Chemung group, or Upper Devon- 

 ian, are related to some of the Coal-Measures, especially in the section of 

 the Ifeuropteridxe ; they differ, however, in their general facies and their 

 specific and even generic characters. The Devonian type of the ferns 

 passes up into the Umbral or Subcarboniferous formation of Pennsyl- 

 vania; while in the West, where the Subcarboniferous is composed of a 

 succession of limestone and sandstone strata, its flora is, on the whole, 

 of the same type as that of the coal, though of course limited to a far 

 less number of representatives. We have, then, in the East a Subcar- 

 boniferous flora of Devonian character; while in the West the formation 

 which is considered as of the same age is with few exceptions of the Car- 

 boniferous type. The difference is attributable to that of the composi- 

 tion and of the formation of the strata. 



The land flora of the Carboniferous period is known by the great 

 quantity of fossil remains, corresponding, in their proportion, to the 

 prodigious exuberance of a vegetation which has furnished the com- 

 pound materials of the Coal strata. Concerning the character of the 

 plants, the Coal epoch has been named the reign or the period of the 

 Acrogens ; the flora, from the base of the Millstone Grit, or even from the 

 first traces of the lowest beds of the Subcarboniferous to the Permian, 

 being represented especially by species of this class. Ferns, JJJquisetacece, 

 and Lycopodiacece, as remarked already. The ferns are very numerous; 

 nearly three hundred and fifty species have been described by European 

 authors, and hardly half this number, as yet, is recorded from the North 

 American Coal-Measures. They are classed and specially defined by the 

 forms of the fronds and the leaflets and by the nervation. By these charac- 

 ters, the relations of the species of the same period to each other are 

 sufficiently established; bur, not so well to the species living at this time, 

 for the reason that these are generally classified and determined by the 

 fructifications, which are rarely found in a fossil state, or not preserved 

 distinctly enough to afford trustworthy points of comparison. 



The first and most interesting group of these ferns of the Carbonif- 

 erous measures is that of the Neuropteridce, mostly representing bush- 

 ferns of great size, whose widely-expanded fronds, many times branch- 

 ing, had compound leaves, with large cordate leaflets and a close flabel- 

 late nervation ; their veins being either straight or curved backward to 

 the borders, dichotomous or forked in ascending. The leaflets, which 

 are generally found isolated or detached from the rachis when petrified, 

 are in some roof-shales heaped and pressed upon one another in innu- 

 merable number, and thus, at first, they appear as if derived from trees; 

 but in some localities, as at Pomeroy, Ohio, for example, the roof of the 

 coal when exposed by the miners looks like a petrified ground, strewn 

 with stems, branches, and leaflets of the same genus, without any trace 

 of trunks. Some of the bushy stems (rachis of fronds) measure at the 



*Ttie presence of Conifers in the Carboniferous measures is, however, indicated, 

 though less positively, by other kinds of organs, as remarked hereafter. 



