78 



CANADIAN FOSSILS. 



(4) Belaiions to Older Florat, 



As already stated in the opening of these remarks, the close of the- 

 Upper Silurian Period in Eastern America was a time of minimum 

 extent of land. Hence, the Upper Silurian beds, immediately under the 

 Devonian, are decidedly marine, and in entering them we not only pass to 

 older rocks, but also recede from the land, so that for both these reasons 

 we might expect to find a great diminution in the number of land plants. 

 Further, in accordance with the views which have been so well illustrated 

 by Prof. Hall as to the derivation of American Silurian sediment from th» 

 North-east, and the gradual extension in each succeeding period of land 

 and shallow water to the South-west, we should expect to find the oldest 

 land-plants toward the North-east. 



Accordingly it is in Gasp^ that as yet we have the only link of connec- 

 tion of the Brian Flora with that of the Silurian period. .In the marine 

 limestones of Cape Gasp^, holding shells and corals of Lower Helderberg 

 age, along with some indeterminable plants, probably fucoids, we have, as 

 already stated, fragmental stems and distinct rhizomes oi Piilophyton, 

 some of them showing the scalariform axis well preserved. These frag- 

 ments must have been drifted from the lard, and as in the immediately 

 succeeding Lower Devonian heda, Pailophyton is associated with Prototao 

 itet, Arthrostigma, and Oalumites, but is the most abundant of the whole, it 

 is not unlikely that in the Upper Silurian land it was associated with plants 

 of these genera. 



Nor is it necessary to suppose that the duration of the existence of the 

 plants represented by these fragments was short. In the modern Pacific 

 the area of land is very small, and few remains of land-plants are pro- 

 bably preserved in the marine deposits now in progress. But if that great 

 basin were elevated, so that much low land would exist in it, and also 

 wide spaces of shallow water with ^nuddy bottoms charged wi imeroug 

 land-plants, it would not be fair to assume that the comparatively sparse 

 vegetable remains of the lower marine beds represented either a very 

 meagre flora or one of short du/ation. The same reasoning would apply 

 to the Lower Helderberg limeswnes as compared with the succeeding Gasp6 

 Sandstones. More especially would this be the case if the plants in ques- 

 tion belonged to an older flora migrating from the nortli-eastward, as the 

 new lands laid bare at the beginning of the Devonian Pjriod gradually rose 

 above the waters. 



In any case, these well characterised Upper Silurian land-plants^ 

 described by me in 1863,* distinctly prove that before the disappearance of 

 the Upper Silurian marine fauna, or of the ocean in which it lived, there 



• Journal of Geol. Society, XIX. 



