296 



Royal Society : — 



The Primordial stage of Barrande (Taconic of Emmons) is truly 

 Silurian, and forms the base of that epoch. 



In the valley of the St. Lawrence it may average 8600 feet in 

 thickness. 



Resting horizontally in America on the inclined Laurentian rocks, 

 the lower break is complete in every respect ; while the upper break 

 is very nearly so, although purely organic. 



It divides naturally into Lower and Upper Primordial, — Potsdam 

 sandstone constituting the former, and calciferous sandstone, with 

 the enigmatical Quebec group, the latter, with a few layers of chazy 

 limestone superadded. 



The whole flora and fauna of the Primordial stage, American and 

 European, amount to 919 species, while those of the St. Lawrence 

 Valley alone are .560. The western, therefore, seems to be the richer 

 of the two hemispheres ; and this comes out still more distinctly in 

 stating the fact that the Primordial genera at present known in 

 America are 134, and those of all Europe 83. 



Table D (below) has been constructed from the * Thesaurus.' It 

 exhibits numerically the zoological contents and the zoological rela- 

 tions of the several parts of the Primordial stage ; and we see that 

 the differences are great. 



Table D. — The American Flora and Fauna of the Primordial 

 Stage (principally Canadian). 



m 



C8 rQ 



wo H 



{Quebec Group . . . 

 Calciferous Sandst. 

 Lower Potsdam Sandstone 



1944 



5 

 2 



57 



4234 96 



619 

 31 



327 



93 



140 



560 



Total 



22 



11 



28 



2645 



99 



79 5317611 



Great interest attaches to every part of this stage, but especially 

 to the Quebec group and its ill-understood connexion with the im- 

 mediately contiguous strata. 



An intimate acquaintance with this group near Quebec leads 

 me to believe that there, at least, it is a displaced, crumpled, and 

 fractured mass of schist, with thin beds of limestone and calcareous 

 conglomerate interleaved, the last crowded with moUuscan and crus- 

 tacean life. 



It is above the Potsdam Sandstone, and on or near the horizon 

 of Calciferous sandstone and the lower layers of Chazy Limestone 

 (Logan and Billings, Report, 1863). Into these (with a distinct 

 tendency still higher), in other parts of North America, the Quebec 



