418 THE CANADIAN NATURALIST. [Vol. Vl. 



by the whole of the rocks from the base of the Utica slate, 

 downward, with the probable exception of the Potsdam sand- 

 stone; while he conceived, partly on lithological grounds, that 

 the Utica and Hudson-E,iver groups represented the Llandeilo 

 and Caradoc, or the Lower Silurian of Murchison [loc, cit. pages 

 20, 29, 31]. The origin of the Cambrian and Silurian con- 

 troversy, and the errors by which the Llandeilo and a part of the 

 Caradoc had by Murchison been classed as a series distinct from 

 the Bala group, were not then known ; but in a note to this 

 report [page 20,] Hall informs us of the declaration of Murchison, 

 already quoted from his address of 1842, that the Cambrian, so 

 far as then known, could not, on paleontological grounds, be dis- 

 tinguished from his Lower Silurian. 



Emmons meanwhile had examined in eastern New York and 

 western New England a series of fossiliferous rocks, which on 

 lithological and stratigraphical grounds, he regarded as older than 

 any in the New York system ; a view which had been previously 

 maintained by Eaton. Holding, with Hall, that the lower 

 members of the New York system were the equivalents of the 

 Upper Cambrian of Sedgwick, he looked upon the fossiliferous 

 rocks which he placed beneath them, as the representatives of the 

 Lower Cambrian. By this name, as we have seen, Sedgwick, in 

 1838, designated all those uncrystalline rocks of North Wales 

 which he subsequently divided into Lower and Middle Cam- 

 brian, and which lie beneath the base of the Bala group. When 

 Murchison, in 1842, in his so often quoted declaration, asserted 

 that " the term Cambrian must cease to be used in zoological 

 classification, it being in that sense synonymous with Lower Si- 

 lurian," he was speaking only on paleontological grounds, and, 

 disregardins: the o-reat Lower and Middle Cambrian divisions of 

 Sedgwick, had reference only to the Upper Cambrian. This how- 

 ever was overlooked by Emmons, who feeling satisfied that the 

 sedimentary rocks which he had examined in eastern New York 

 were distinct from those which he, with Hall, regarded as corres- 

 ponding to the Bala group or Upper Cambrian, (the Lower 

 Silurian of Murchison), and probably equivalent to the inferior 

 portions of Sedgwick's Cambrian ; and supposing that the latter 

 term was henceforth to be effaced from geology (as indeed was 

 attempted shortly after, in the copy of Sedgwick's map published 

 in 1844 by the Geological Society) devised for these rocks the 

 name of the Taconic system, as synonymous with the Lower 



