LAURENTIAN AND EARLY PALEOZOIC. 



37 



fronds smooth and slightly striate longitudinally, with 

 curved and intermixed stria). kStem thick, bifurcating, 

 the divisions terminating in irregularly pinnate fronds, 

 apparently truncate at the extremities. The quan- 

 tity of carbona- 

 ceons matter pres- 

 ent would indicate 

 thick, though per- 

 haps flattened, 

 stems and dense 

 fleshy fronds. 



The species 

 Butliotrcphis sub- 

 nodosa and B. 

 jlexuosa, from 

 the Utica shale, 

 are also certain- 

 ly plants, though 

 it is possible, if 

 their structures 

 and fruit were 

 known, some of 

 these might be 

 referred to differ- 

 ent genera. All 

 of these plants 

 have either car- 

 bonacGous matter 

 or produce organ- 

 ic stains on the 

 matrix. 



The organism 



Fio. 13. — Buffi of rep /lift Grnnfii, u j»enuinc Alga 

 frum the Siluriun, Ciinuda. 



diverging 



with 



wedge-shaped fronds, described by Hall as Sphenothalhis 

 aiKjustifolius, is alsc -i. plant. Fine specimens, in the 

 collection of the Geologic^,! Survey of Canada, show dis- 



