60 SECTIONAL ADDRESSES. 



been miles and miles of foreshore, exposed between tides, where fishes, 

 cut off in the mud, gasped air, until the water came over their gills again, 

 and the undertow carried them back into the depths. But in fossili- 

 f erous times until the Devonian, there was little dry land ; and there were 

 no undisturbed shallow marshes, where water animals and plants could 

 learn to do without water. 



We said ' in fossilif erous times.' It is not fitting for one who is not a 

 geologist to do more than touch very lightly on the problems of the Pre- 

 Cambrian. But connected with them is an interesting consideration to 

 which I would draw the attention of fellow-biologists. If we follow the 

 American geologists '° in attributing organic origin to the graphites of the 

 Grenville series at the base of the Laurentian — which are stated by Dawson 

 to contain as much carbon as the whole American coal-measures, and with 

 which we may class the graphite schists described by Geikie 6 under the 

 Scottish Lewisian, and the seven feet of so-called ' anthracite ' found in 

 Finland by Sederholm 7 in the Jatulian, at least three miles under the 

 Cambrian — I do not see how we can avoid the conclusion that there was 

 vegetation growing in or about quiet landlocked waters, for many thousands 

 of years, as long before the Cambrian as the Cambrian was before us. 

 Among palaeontologists the view prevails that it is in such still landlocked 

 waters that rapid evolution has always taken place. It seems impossible 

 not to believe that a terrestrial flora, and a terrestrial fauna, must have 

 been evolved in those favourable times and the long ages which followed, 

 to be swept to destruction in the deluge that denuded the Torridonian. 

 If so, we see in the succession of Cambrian and Ordovician fossils — the 

 ' marine period ' of the Palaeozoic, as Marr 8 designates it — the development 

 for a second time of a littoral from a deep-sea fauna ; which fits closely with 

 Walcott's conclusions on the Cambrian." And in the Silurian and 

 Devonian we see the evolution of a terrestrial flora and fauna for the 

 second time. 



If all the Pre-Cambrian lands were swept by fierce and terrible torrents, 

 marine organisms might nevertheless survive in the deep abysses of the 

 sea, to recolonise later the still-vexed Cambrian shores. It is also con- 

 ceivable that exceptional organisms might survive in the tranquil abysses 

 of the high air, or on the occasional mountain-tops ; and the fancy has 

 struck me that such isolated survivors from the ancient sub-aerial popula- 

 tion may conceivably be recognised in the progenitor of the Ordovician 

 winged insects, and in the ancestor to Hugh Miller's conifer of the Old 

 Red Sandstone. 10 



Leaving the geologists and botanists to settle for us the truth or error 



5 C. Schuehert, Pirsson and Schuchert's Text-book, vol. ii, p. 545. New York, 1920. 

 A. Geikie, I.e. p. 890. » Nature, 1908, p. 266. 



8 ' Principles of Stratigraphical Geology,' p. 149. Cambridge, 1905, University Press. 



9 He believes that before the Cambrian there was an era, ' of unknown marine 

 sedimentation between the adjustment of pelagic life to littoral conditions and the 

 appearance of the Lower Cambrian fauna.' Quoted by Schuchert, I.e. p. 570. 



10 Compare D. H. Scott, 1924 : ' Extinct Plants,' p. 181. London, Macmillan. 

 In America the denudation before the Cambrian marks the ' third Great Erosion 



Interval.' The Grenville coal was before all these ; Grabau (p. 203) puts Jatulian 

 between the second and third. 



