62 THE CANADIAN NATURALIST. [Vol. 



Til. 



Thus were painfully unfolded the Cambrian and Silurian sys- 

 tems, which speedily became, in a sense, the scientific property 

 of the discoverers, and were supposed to be firmly separated by- 

 natural and unmistakeable boundaries. They were, however,. 

 not really traced to their junction, though Murchison stated that 

 he had found many distinct passages from the lowest member of 

 the Silurian system into the underlying slaty rocks named by 

 Prof. Sedgwick the ''Upper Cambrian;" while Sedgwick 

 admitted that his upper Cambrian, occupying the Berwyns, was 

 connected with the Llandeilo flags of the Silurian system, and 

 thence expanded through a considerable portion of South Wales 

 (Reports of Brit. Assoc, 1835) . The Bala rocks were disclaimed 

 on a cursory view by Murchison, the Llandeilo beds surrendered 

 without sufficient examination by Sedgwick ; thus the tw^o king- 

 doms overlapped largely ; two classifications gradually appeared -y^ 

 the grand volume of Murchison was issued ; and then began by 

 degrees a diiference of opinion which finally assumed a controver- 

 sial aspect, always to be deplored between two of the most truly 

 attached and mutually helpful cultivators of geological science in 



Ensiland : — 



" Ambo animis, ambo insignes pra'istantibus armis."' 



This source of lasting sorrow to both, if it cannot be forgotten, 

 ought to be only remembered with the tenderness of regret. 



Familiar as we now are with the rich fauna of the Cambrian, 

 and Silurian rocks, and their equivalents in Bohemia and 

 America, it is not difficult to understand, and we may almost feel 

 asain the sustained enthusiasm which welcomed the discoveries 

 which seemed to reveal the first state of the sea, and the earliest 

 series of marine life '' primaque ab origine mundi," almost to- 

 complete the physical history of the earth. Starting with a 

 o:eneral view of the structure of the Lake Mountains of the north 

 of England, and the great dislocations by which they have been 

 separated from the neighbouring chains (Geol. Proc. Jan. 1831). 

 Sedgwick won his difficult way through North Wales to a general 

 synopsis of the series of stratified rocks below the Old Bed sand- 

 stone, and attempted to determine the natural groups and forma- 

 tions (GeoL Proc. May, 1838). Three systems were named in 

 order — Lower Cambrian, Upper Cambrian, Silurian — the work- 

 ing out of which, stream by stream, and hill by hill, worthily 

 tasked the energies of Bamsay and his friends of the National 

 Survey for many useful years, after increasing ill-health had 

 much reduced the field-work of the Professor. 



