FOSSIL PLANTS. 505 



with coal No. 2. Hymenophyllites furcatus has more generally been found be- 

 low the Millstone grit, but it ascends, though rarely, to coal No. 2, where also 

 Hymenopliyllites splendens, If. Scklotheimii and some other species of the section 

 Aphlebia are generally found. 



As representative of the higher coal strata of Illinois, or of coal No. 5, there 

 is no particular species to quote. AletTiopteris aquilina, with Pecopteris unita, P. 

 plumosa, Cordaites angustifolia, and species of Lepidophloios, are there repre- 

 sented by more abundant specimens than anywhere else, but remains of these 

 plants have been also observed in the lower Coal Measures. In the anthracite 

 basin of Pennsylvania, the highest strata are recognized by the presence of 

 Pecopteris arborescens, which has not been as yet positively discovered in Illi- 

 nois, the small specimens referred to it from a nodule of Mazon creek being 

 too obscure for certain identification; This species, the most abundant of all 

 in some localities of Pennsylvania, is found also in profusion in the red clay 

 beds of Ohio, especially in the grotto of flowers, near Marietta, where it is 

 represented by a slightly different form, perhaps a mere variety of P. rubra, 

 Lesqx. In Europe, it ascends to the Permian, where its characters, though 

 somewhat modified, have been considered as specific by Goppert, who has 

 named it P. ( Cyatheites) Sclilotheimii. It is there, as with us, associated with 

 its large form P. Cyathea, Brgt. The section Cyatheites of the genus Pecopte- 

 ri&, is, indeed, of all the fossil ferns of the coal, the one which is, in some of 

 its species, characteristic of the higher coal strata. But as yet these species 

 are indifferently known, and therefore it is hardly possible to indicate them as 

 peculiar to a certain horizon. For example, Pecopteris polymorpha, Brgt., 

 abounds in the highest coal strata of Illinois at Grayville, and near New Har- 

 mony, Ind. It is generally like P. arborescens, a marked species of our upper 

 Coal Measures, while Pecopteris abbrcviata, which Prof. Geinitz takes as a 

 mere variety of it, is common at Morris, Mazon creek and other places, always 

 in connection with coal No. 2, and has not yet been observed in higher strata. 

 The differences in these horizons, as well as in the form of the pinnae, indicate 

 these remains as representing two different species, though the nervation is of 

 the same kind. It is certain that, as the Lycopodiaceous plants of the coal 

 decrease in the number of their representatives, as in their size, in ascending 

 in the Coal Measures, they are proportionally replaced by ferns, either herba- 

 ceous or arborescent. This change is everywhere evident in the shale over- 

 laying the coal beds, as in the coal itself. At Grayville, and especially at 

 Springfield, 111., where the upper coal is nearly 200 feet above coal No. 5, 

 the lamellae of the coal bear a quantity of recognizable leaflets and branches 

 of ferns, especially of the genus Pecopteris. The roof shales of the Pomroy 

 coal in Ohio are thickly covered with remains of ferns, especially large'pinnje, 

 still bearing leaves of Neuropteris flexuosa and N. hirsuta. A bed of shale, 

 64 



