Some Palceobotanical Asioects. 279 



the Appalachian basins, must have been clothed through- 

 out by the general tlora characteristic of the particular 

 geological time ; and on the occasions of the great floral 

 changes of the earth it should, with the important aid of 

 air and water currents, have carried migrating species so 

 rapidly from shore to shore that the period of each suc- 

 cessive flora would be essentially contemporaneous in 

 either basin. In view of these relations only undeniable 

 stratigraphic evidence can prove that the identical floras 

 do not belong to tlie same great period, and that we have 

 in Nova Scotia the unique phenomenon of a typical middle 

 Carboniferous flora in rocks of the middle Devonian. 

 Such an occurrence, as yet unknown elsewhere in North 

 America or Europe, and in direct contradiction of all bio- 

 pakeobotanical data, would scarcely be harder to explain 

 for one district than would it be to account for its absence 

 in other regions of the Northern hemisphere. 



The existence of the wide erulf between the correlations 

 by stratigraphy and those by palpeontology does not admit 

 of the conclusion that the verdict of the stratigraphers is 

 final. With all respect for their ability and the conscien- 

 tious character of their work in a field offering great 

 difficulties of surface concealment, it is still proper to 

 enquire of the Nova Scotia geologists if there is not a fur- 

 ther stratigraphical explanation ; whether, for instance, 

 certain plant beds at different points may not have been 

 wrongly correlated in carrying the stratigraphical identi- 

 fications across to the type (reference) sections ; or whether 

 the Carboniferous Limestone of their sections is not much 

 younger than is generally supposed ; or whether certain 

 of the superpositions are not possibly due to overthrust 

 faulting. 



Note of Explanation. 



A seeming discrepancy between Mr. Kidston's and my 

 own correlations of the Riversdale-Harrington River plants 



