444 THE CANADIAN NATURALIST. [Vol. vi. 



subsequent ones for 1844 and 1846, adopted the nomenclature 

 of the New York system, without reference to European divi- 

 sions. Subsequently however, the usage of Lyell and de Verneuil 

 was adopted by Logan, who in his report for 1848 (page 57) 

 spoke of the Clinton group as the base of the "■ Upper Silurian 

 series," while in that for 1850 (page 34) he declared the whole 

 of a great series of fossiliferous rocks in Eastern Canada, includ- 

 ing the Trenton, TJtica and Hudson-River divisions, and the 

 shales and sandstones of Quebec, (then supposed to be superior 

 to these,) to "belong to the Lower Silurian." In the report for 

 1852 (page 64) the Lower Silurian was made by Mr. Murray to 

 include not only the Utica and Trenton, but the Chazy limestone, 

 the Calciferous sandrock and the Potsdam sandstone of the New 

 York system. From this time the Silurian nomenclature, as 

 applied by Lyell and de Verneuil to our North American rocks, 

 was employed by the officers of the Canadian Geological Survey 

 (myself among the others,) and was subsequently adopted by 

 Prof. Dana in his Manual of Geology, published in 1863. 



The Geological Survey of Pennsylvania, under the direction 

 of Prof. Henry Darwin Rogers, was begun, like that of New 

 York, in 1836, and the paleozoic rocks of the state were at first 

 divided, on stratigraphical and lithological grounds, into groups, 

 which were designated, in ascending order, by Roman numerals. 

 Subsequently, as he informs us in the preface to his final Report 

 on the Geology of Pennsylvania, Prof. H. D. Rogers, in concert 

 with his brother. Prof William B. Rogers, then directing the 

 Geological Survey of Virginia, considered the question of geolo- 

 gical nomenclature. Rejecting, after mature deliberation, the 

 classification and nomenclature both of the British and New 

 York Geological Surveys they proposed a new one for the whole 

 paleozoic column to the top of the coal-measures, founded on the 

 conception of a great paleozoic day, the divisions of which were 

 designated by names taken from the sun's apparent course 

 through the heavens. (Geology of Penn. I. vi, 105.) So far as 

 regards the three great groups which we have recognized in the 

 lower paleozoic rocks, the later names of Rogers, and his earlier 

 numerical designations, with their equivalents in the New York 

 system, were as follows : 



Primal, (I.) This includes the mass of 2500 feet or more of 

 shales and sandstones, which in Pennsylvania and Virginia, and 

 farther southward, form the base of the paleozoic series, and rest 



