446 THE CANADIAN NATURALIST. [Vol. vi. 



The reader of the List few pages of this history will have seen 

 how tlie Silurian nomenclature of Murchison and the British 

 Geological Survey has been, through Lyell. de Verneuil and the 

 Canadian Survey, introduced into American geology in opposi- 

 tion to the judgment, and against the protests of James Hall and 

 the Messrs. Kogers, the founders of American paleozoic geology. 



Three points have I think, been made clear in the first and 

 second parts of this sketch : First, that the series, to which the name 

 of Cambrian was applied by Sedgwick in 1835, (limited by him 

 as to its downward extension, in 1838) was co-extensive with the 

 rocks characterized by the first and second faunas. Second, that 

 the series to which the name of Silurian was given by Murchison 

 in 1835, included the second and third faunas; but that the 

 rocks of the second fauna, the Upper Cambrian of Sedgwick, 

 were only included in the Silurian system of Murchison by a 

 series of errors and misconceptions in stratigraphy, on the part 

 of the latter, which gave him no right to claim the rocks of the 

 second fauna as a lower member of his Silurian. Third, that 

 there was no ground whatever for subsequently annexing to the 

 Silurian of Murchison, the Lower and Middle Cambrian divi- 

 sions of Sedgwick, which the latter had separated from the Upper 

 Cambrian on stratigraphical grounds, and which were subse- 

 quently found to contain a distinct and more ancient fauna. 



The name of Silurian should therefore be restricted, as main- 

 tained by Sedgwick and by the Messrs. Rogers, to the rocks of 

 the third fauna, the so-called Upper Silurian of Murchison ; and 

 the names of Middle Silurian, Lower Silurian, and Primordial - 

 Silurian banished from our nomenclature. The Cambrian of 

 Sedgwick however includes the rocks both of the first aod second 

 faunas. To the former of these, the lower and middle divisions of 

 the Cambrian, (the Bangor and Festiniog groups of Sedgwick,) 

 Phillips, Lyell, Davidson, Harkness, Hicks and other British 

 geologists, agree in applying the name of Cambrian. The great 

 Bala group of Sedgwick, which constitutes his Upper Cambrian, 

 is however as distinct from the last as it is from the overlying 

 Silurian, and deserves a not less distinctive name than these 

 two. Its original designation of Upper Cambrian, given when 

 the zoological importance of Lower and Middle Cambrian was 

 as yet unknown, is not sufiiciently characteristic, and the same 

 is to be said of the name of Lower Silurian, wrongly imposed 



