in the Coal Formation at Wardte. 147 



to have been changed from their original position by some after 

 action. 



Many interesting geological phenomena are seen in this beau- 

 tiful section, which we cannot notice at present, as we purpose 

 confining our attention chiefly to the imbedded fossil organic 

 remains. We shall first describe the fossil plants, and after- 

 wards notice the fossil remains of animals. 



1. Fossil Plants. 



They generally occur in the form of impressions, more rarely 

 in that of casts, the latter being frequently composed of a centre 

 of iron-pyrites, with a surface of bituminous matter, while in 

 others they are entirely formed of a substance resembling jet, 

 the external part of which is of a soft texture, bearing, however, 

 the different vegetable markings distinct upon it. 



In this place, like the other coal-fields which have been exa- 

 mined, the majority of the vegetable remains may be referred 

 to the tribe of Ferns. Brongniart, indeed, estimates that two- 

 thirds of the coal formation flora, belong to this class of plants. 

 The species of Filices may be referred to three genera, viz. 

 SphenopteriSy Cyclopteris, and Neuropteris. 



I. Genus Sphenopteris. The most abundant species of 

 this genus is the affinis ; it occurs almost universally dissemi- 

 nated through the shale, not being confined to any particular 

 stratum ; the best specimens, however, are always to be found 

 at the point where a thin layer of clay ironstone joins the shale. 

 The Sphenopteris crythmi/blia, S. artemisice/blia, S.Jtircata, S. 

 elegans, S. Hoenuigkaiisi, are also occasionally found, but in 

 more sparing quantities than the affinis. Of the four first in 

 order of these species, it may be remarked that they bear a 

 great resemblance to each other, some authors, indeed, classify- 

 ing them all under one head, the affinis. 



Although it is difficult to distinguish them, the determination 

 may be made by a minute inspection of their nervures, and by 

 reference to good plates, as those in the works of Brongniart, and 

 the British Fossil Flora by Messrs Lindley and Hutton. 



II. Genus Cychptcris. This genus, which is the next in 

 point of abundance, equal.«, if it does not surpass, the sphenop- 



k2 



