PRE-CARBONIFEROUB PLANTS. 



T^. 



already existed land clothed with at least one genus of Lycopodiaceous plants^. 

 and this the same which ' irgely predominates in the succeeding Lower 

 Devonian, in which, however, these plants, occurring merely as drifted 

 fragments in the Upper Silurian limestones, are found in vast numbers in 

 a perfect state of preservation, '-.nd rooted in the soil in which they 

 grew. 



Below the Upper Silurian our knowledge of the land flora in Eastern 

 America altogether fails. Notwithstanding the evidence of shallow- water 

 conditions on the flanks of the Appalachians, in the conglomerates and 

 sandstones of the base of the Upper Silurian, no land-plants have been 

 found in these beds ; and though in the Lower Silurian the Potsdam sand- 

 stone, skirting the base of the old Laurentian nucleus, must have been 

 formed near the shore, and sometimes abounds in carbonized fragments, 

 perhaps of fucoids, no certain traces of land-plants have been found in it. 

 This is the more remarkable since m some portions of the Lower Silurian 

 period a broad surface of land must have existed in the northern part of 

 Canada. Could we discover the estuaries of any of the streams which 

 flowed from this old land, some hope might be entertained of the discovery 

 of terrestrial vegetation. If, however, with Prof. Hall, we regard the 

 origin of the Silurian sediments and of the land flora to have been in the 

 north-east, it is possible th.it the rocks of Newfoundland or Labrador, or 

 beds now buried under the Atlantic, may be those which alone contain the 

 remains of the Lower Silurian plants. 



In Europe the precursors of the Devonian flora are better known than 

 in America. The Paehytheca of Hooker from the Ludlow Bone-Bed, may 

 be regarded as of similar age with the Psilophyton of the Gasp6 limestone y 

 and like it probably Lycopodiaceous. Of equally ancient date are the 

 Sagenarios (^Lepidodendra) discovered by Geinitz in the Upper Silurian 

 of Lobenstein, and by Barrande in that t)f Hosten, Bohemia, and the 

 Hostinella of Burr from the last mentioned locality.* The Eopkyton of 

 Torrell, from a much lower horizon in Sweden, I regard as a doubtful plant, 

 similar forms being apparently produced by impressions of feet or fins on 

 the surface of mud. If a land -plant, however, the E. Linoeanum is more 

 nearly allied to Fsilophyton than to any other genus. Whatever the 

 nature of these forms, they are present in the Primordial of America as well. 

 Mr. Murray has found them in Newfoundland and Mr. Selwyn in Nova 

 Scotia, in rocks probably of this age. The E. explanatum of Mr. Hicks from 

 the Lower Areiiig rocks of Wales is apparently something quite different, 

 and its microscopic structure would seem to be similar to that of the 

 Nematoxylon of the Devonian, if it is a plant at all, and not a marine 



* fiigsby'g Thesaurus iSUuricus, p. 19i. 



