rOSSIL FLORA. 81 



PLATE XXXII. 

 " Decurrent Filicite." 



[Alethopteris decurrens, of Goppert. 

 Pecopteris heterophylla, Lindley and Hutton, tab. 38. 



Filicites decurrens, of Artis. ) 



The drawing represents but a small portion of the specimen, which indicated a plant of 

 gigantic size. 



" The leaf or frond of this fern is very large, tripinnate or quadripinnate ; the stipes is broad 

 and undulated ; the leaflets are sessile, linear-lanceolate ; the ribs pinnate, the secondary ribs 

 perpendicular to the main rib ; the first leaflet on the superior side of the pinnule adheres by its 

 side to the rachis." — Artis. 



This fern, which closely resembles some recent species, {Pteris aurita,) occurs in great 

 abundance in the shale at Alverthorpe near Wakefield. Notwithstanding the profusion with 

 which the foliage of many kinds of ferns is distributed throughout the coal formation, the 

 undoubted stems of tree-ferns are so rare, that it may admit of question whether some of the 

 leaves which from the analogy of their structure to recent forms have been referred to the ferns, 

 may not have belonged to the stems of unknown trees with which they are associated in the 

 strata ; for as, in the animal kingdom, distinct types of living organisms are often found blended 

 in the extinct races, so in the vegetable, it is possible, that foliage and stems, of apparently 

 discordant types, may have belonged to the same extinct species or genus of trees. This 

 problem can only be solved by diligent and continued research in the richest localities of 

 coal-plants. 



M. Brongniart remarks that every bed of coal is the product of a special vegetation, often 

 difierent from that which preceded, and that which followed it. Each bed thus resulting from a 

 distinct vegetation, is characterized by the predominance of certain impressions of plants, and the 

 experienced miners distinguish in many cases the beds they are working, by their practical 

 knowledge of the plants that prevail. 



The same beds of coal, and the deposits which cover it, ought therefore to contain the 

 different parts of the plants that were living at the period of its formation ; and by carefully 

 studying the association of these different fossils, forming thus little special floras, generall}- of 

 but few species, we may hope to acquire data by which we may advance the means of recon- 

 structing the anomalous vegetable forms of the ancient world. M. Brongniart strongly urges 

 attention to this circumstance in the examination of the coal strata, with the view of determining 

 the identity of the scattered leaves, stems, and fruits, in any particular stratum. By such a 

 procedure, much addition would be made to our knowledge of the entire structures of many of 

 the fossil plants of which we now only know the fragments. Thus we may hope to ascertain the 

 foliage of the Sigillarias, the roots of which, by a similar method, have but recently been 

 determined to be the fossils called Stigmarice. 



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