564 Geological Society, 



consideration of such conclusions of general geological interest as 

 can be drawn from the accumulated data. Heference was made 

 to the views of Dr. Church on the origin of life in tjie waters 

 of a primeval world -ocean, and on the origin of terrestrial vege- 

 tation from highly-organized Algae transferred by emergence 

 of portions of the Earth's crust above the surface of the water 

 from an existence on the ocean-floor to life on land. It was 

 suggested that the vegetation of the land may have received 

 additions from upraised portions of the crust at more than one 

 epoch in the history of the Earth. The course of evolution could 

 probably be more correctly illustrated by the conception of separate 

 lines of development, than by that of a branching tree implying 

 the common origin of the main groups of plants. The unfolding 

 of plant-life must be considered in relation to the changing 

 geological background. The climatic and physical conditions of 

 the Pre-Cambrian Era were briefly considered, and various kinds 

 of indirect evidence of the existence of plant-life were critically 

 examined : reference was made to graphite, supposed algal remains 

 in association with oolitic structure, Cryptozoon, and the structures 

 described by Dr. C. D. Walcott as Algae or as the result of algal 

 agency. Attention was called to the importance of carefully 

 investigating diffusion-phenomena, as illustrated by the so-called 

 Liesegang figures, as a possible explanation of the origin of 

 some of the structures which are usually attributed to organic 

 agency. We have no knowledge of an}^ Pre-Cambrian land-flora. 

 Palseobotanical records from Cambrian, Ordovician, and Silurian 

 strata were briefly summarized, including some account of 

 Girvanellay l^^opliyton, Solenopora, Nematopliycus, PacJiytheccty 

 and JParka. Keasons were given for assigning some of the 

 Cambrian Algae described by Dr. Walcott to the Cyanophycese, 

 especially Marpolia spissa. 



In the second part of the Address, the older Devonian floras 

 were reviewed, and some of the more characteristic genera de- 

 scribed, special attention being directed to the petrified plants from 

 the Bhj'nie chert-bed, discovered by Dr. W. Mackie, and described 

 in detail by Dr. P. Kidston and Prof. W. H. Lang. Reference 

 was made to the differences between the older Devonian floras and 

 those of Upper Devonian age. The question of the common origin 

 of the phyla of Lycopods and Ferns was considered, and preference 

 was expressed for the view which regards them as independently- 

 evolved groups. In conclusion, the wide geographical range of 

 AixJiceopferis was emphasized, and reference was made to the 

 diflicult problems raised by the occurrence of Upper Devonian 

 floras well within the Arctic circle, at least equal (in the variety of 

 the plants and in the vigorous development of the vegetation) 

 to the more southern floras of Ireland, Belgium, and other 



