THE FOUNDATIONS OF THE CONTINENTS lOI 



" There is thus no absolute impossibility that 

 distinct organic tissues may be found in the Lau- 

 rentian graphite, if formed from land-plants, more 

 especially if any plants existed at that time having 

 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- 

 rentian 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- 

 tinguish the remains of land-plants from those of 

 Algae. The only apparent plant of the Laurentian 

 to which a name has been given. Arch cBophy ton of 

 Britton, from New Jersey, consists of ribbon-like 

 strips, 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- 

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

 the limestone of the Grenville 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 



