190 PROCEEDINGS OP THE AMERICAN ACADEMY 



The idea of Prof. Hitchcock that the Berkshire marbles are De- 

 vonian is a great way from the truth ; because, in the range of 

 mountains between New York and Massachusetts, this limestone lies 

 below the slates which run up into those containing the primordial 

 trilobites. 



" The acknowledgment of the Primordial of Barrande in this 

 country is really one of the finest and best facts in geology, making a 

 co-ordination of American and European rocks so complete and har- 

 monious ; I think of nothing I have said or done in this matter; I 

 look upon the harmony of the systems ; they are truly worth dwelling 

 upon ; and a great deal more is yet to come out. 



" I want much to see you when I get to Albany in the spring, to 

 look over with me my fossils from the Trias and Dyas. — By the way, 

 this puts me in mind of the Dyas controversy with Murchison ; and 

 I think you have got the better of the old Dictator ; and the Dyas 

 must stand and take the place of Permian. 



" E. Emmons." 



" Ealeigh, January 28, 1861. 

 " Prof. J. Marcou. 



"My DEAR Sir, — You will excuse me for addressing you at this 

 time, or again, inasmuch as my letters, I fear, may get to be trouble- 

 some. But I wish to say two or three things about your proposition 

 to place the Potsdam sandstone at the top of Barrande's Primordial 

 group or my Taconic system. Let me declare, once for all, that I 

 have not the slightest objections to your view; as if when established 

 it would diminish aught of the importance of my views ; but simply 

 to present something for your consideration before the Potsdam rock, 

 as I established it in 1836-37, is abandoned as the base of the Silu- 

 rian system. 



*•' In St. Lawrence and Jefferson Counties, where first observed, it 

 is underlaid by beds of coarse granitic conglomerate, and then gradu- 

 ating into a fine even-grained sandstone, and then the sandstone grad- 

 uating again into the Calciferous sandstone above, the latter of which 

 is perfectly conformable,* so that there is no line really of demarca- 

 tion between the Potsdam and the Calciferous. Now in the region I 

 have named I see no possibility of excluding the Potsdam from the 

 Silurian system, and there are no fossils except a single Lingula 



* It is a mistake. I have observed since at Chazy and Potsdam a discord- 

 ance of Btratification of 16'^ between the Potsdam sandstone and the Calciferous 

 sandrock. — J. M. 



