THE FOUNDATIONS OF THE CONTINENTS lo, 



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"There is thus no absohite impossibility that 

 cl.st,nct organic tissues may be found in the Lau- 

 rent,an graphite, if formed from land-plants, more 

 especially if any plants existed at that time havin- 

 true woody or vascular tissues ; but it cannot with 

 certainty be affirmed that such tissues have been 

 found. It is possible, however, that in the Lau- 

 rent,an period the vegetation of the land may have 

 consisted wholly of cellular plants, as, for example 

 mosses and lichens ; and if so, there would be com- 

 paratively little hope of the distinct preservation of 

 their forms or tissues, or of our being able to dis- 

 tmguish the remains of land-plants from those of 

 Alg^ The only apparent plant of the Laurentian 

 to which a name has been given, ^..te„^^_,„,„ ^f 

 Bntton, from New Jersey, consists of ribbon-like 

 stnps, destitute of apparent structure, and which if 

 they are of vegetable origin, may have belonged to 

 either of the leading divisions of the vegetable king- 

 oom. I have found similar flat frond-like objects in 

 the limestone of the Grcnville series, at Lachute. in 

 Canada. 



"We may sum up these facts and considerations 

 in the following statements :_First, that somewhat 

 obscure traces of organic structure can be detected 



