Geological Address at Manchester. 403 



North American Taconic group of Emmons,* with his own pri- 

 mordial Silurian fauna of Bohemia and other parts of Europe; 

 and, although that sound palaeontologist, Mr. James Hall, has not 

 hitherto quite coincided with M. Barrande in some details,f it is 

 evident that the primordial fauna occurs in many parts of North 

 America. And as the true order of succession has been ascer- 

 tained, we now know that the Taconic group is of the same age 

 as the lower Wisconsin beds described by Dale Owen, with their 

 Paradoxides, Dikellocephalus, &c., as well as of the lower portion 

 of the Quebec rocks, with their Conocephalus, Arionellus, &c., 

 described by Logan and Billings, of the crystalline schists of 

 Massachusetts, containing the noble specimens of Paradoxides de- 

 scribed by W. Rogers, and of the Vermont beds with their Oleni. 

 It follows that the primordial Silurian zone of Barrande (the low- 

 er Lingula flags of Britain) is largely represented in North 

 America, however it may occupy au inverted position in some 

 cases, and in others be altered into crystalline rocks. 



" In determining this question due regard has been had to the 

 great convulsions, inversions, and breaks to which these ancient 

 rocks of North America have been subjected, as described by 

 Professors Henry and W. Kogers. 



" In an able review of this subject, Mr. Sterry Hunt thus ex- 

 presses himself: — * We regard the whole Quebec group, with its 

 underlying primordial shales, as the greatly developed represen- 

 tative of the Potsdam and Calciferous groups (with part of that 

 of Chazy), and the true base of the Silurian system.' * The 

 Quebec group with its underlying shales,' this author adds (and 

 he expresses the opinion of Sir W. Logan,) * is no other than the 

 Taconic system of Emmons ;' which is thus, by these authors, as 

 well as Mr. James Hall, shown to be the natural base of the Si- 

 lurian rocks in America, as Barrande and De Verneuil have 

 proved it to be on the continent of Europe. 



"In our own country a valuable enlargement of our acquaint- 

 ance with the relations of the primordial zone to the overlying 

 members of the Silurian rocks has been made through the per- 

 sonal examination of Mr. Salter, aided by the independent 



* The Silurian classification was proposed by me in 1835, and in the 

 following year, 1836, Dr. Emmons suggested that his black shale rocks 

 which he called Taconic, were older than any I described. 



t Nor are the writings of the Professors W. B. and H. D. Rogers in 

 unison with the opinions of the authors here cited. 



