388 CAMBRIAN AND SILURIAN -IN NORTH AMERICA. [XV. 



on lithological grounds, that the Utica and Hudson-River 

 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 controversy, and the errors by 

 which the Llandeilo and a part of the Caradoc had by Murchi- 

 son 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 palseontological grounds, be distinguished 

 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 JJpper 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 un- 

 crystalline rocks of North Wales which he subsequently divided 

 into Lower and Middle Cambrian, 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 a zoological classification, it being in that 

 sense synonymous with Lower Silurian," he was speaking only 

 on palajontological grounds, and, disregarding the great Lower 

 and Middle Cambrian divisions of Sedgwick, had reference only 

 to the Upper Cambrian. This, however, was overlooked by 

 Emmons, who, feeling satisfied that the sedimentary rocks which 

 lie had examined in eastern New York were distinct from those 

 which he, with Hall, regarded as corresponding 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 



