404 THE CANADIAN NATURALIST. [Vol. vi. 



Thuja occidentalis, Linn, (found at Montreal.) 



Potamogeton 2:)erfoliatus, Linn. 



Equisetum scirj)oides, Miclix. 



Carices and graminece, fragments. 



FontinaUs, sp. 



Algae. 



These plants occur in the marine Leda clay, containing its 

 characteristic fossils, and were probably washed from the neigh- 

 bouring laud by streams. They indicate to some extent the 

 flora of the Laurentian hills bordering the valley of the Ottawa, 

 at the time of the Post-pliocene subsidence. The inferences as 

 to climate deducible from them are stated in the following ex- 

 tract from the paper above referred to : 



" None of the plants above mentioned are properly Arctic in 

 their distribution, and the assemblage may be characterized as a 

 selection from the present Canadian flora of some of the more 

 hardy species having the most northern range. Green's Creek is 

 in the central part of Canada, near to the parallel of 46°, and an 

 accidental selection from its present flora, though it might con- 

 tain the same species found in the nodules, would certainly 

 include with these, or instead of some of them, more southern 

 forms. More especially the balsam poplar, though that tree 

 occurs plentifully on the Ottawa, would not be so predominant. 

 But such an assemblage of drift plants might be furnished by 

 any American stream flowing in the latitude of 50^ to 55*^ north. 

 If a stream flowing to the north it might deposit these plants in 

 still more northern latitudes, as the McKenzie River does now. 

 If flowing to the south it might deposit them to the south of 50^. 

 In the case of the Ottawa, the plants could not have been derived 

 from a more southern locality, nor probably from one very far 

 to the north. We may therefore safely assume that the refri- 

 geration indicated by these plants would place the region bor- 

 dering the Ottawa in nearly the same position with that of the 

 south coast of Labrador fronting on the' Gulf of St. Lawrence, 

 at present. The absence of all the more Arctic species occur- 

 rino- in Labrador, should perhaps induce us to infer a somewhat 

 more mild climate than this."* 



The climatic indications afforded by these plants are not 

 dissimilar from those furnished by a consideration of the marine 

 fauna of the period of l^he Leda clay. 



