382 PROF. HALL'S VIEWS. 



and the black colored shales beneath. The Lake Superior group is the upper copper-bearing series of that 

 region, and rests unconformably upon the lower copper-bearing series, which is the Huronian system. The 

 upper copper-bearing series holds nearly all the metals, including gold, and so does the Quebec group, each 

 making an important metalliferous region. Each when unmetamorphosed holds a vast collection of red 

 colored strata. The want of fossils in the Lake Superior group makes it difficult to draw lines of division, 

 but if any part represents the primordial zone, I should hazard the conjecture that it is the dark colored 

 slates of Kamanistiquia, which underlie all the red rocks. 



Professor Emmons has long maintained, on evidence that has been much disputed, that rocks in Ver- 

 mont, which in June, 1859, I for the first time saw and recognized as equivalent to the magnesian part of 

 the Quebec group, are older than the Birdseye formation; the fossils which have this year been obtained 

 at Quebec pretty clearly demonstrate that in this he is right. It is at the same time satisfactory to find 

 that the view which Mr. Billings expressed to you in his letter of the 12th July, to the eifect that the Que- 

 bec trilobites appeared to him to be about the base of the second fauna, should so well accord with your 

 opinions; and that what we were last spring disposed to regard at Georgia as a colony in the second fauna, 

 should so soon be proved, by the discoveries at Quebec, to be a constituent part of the primordial zone. 



I am, my dear M. Barrande, 



Very truly yours. 



W. E. LOGAN. 



M. JOACHIM BARRANDE, Rue Meziere No. 6, Paris. 



LETTER FROM JAMES HALL, PALEONTOLOGIST OF NEW YORK, TO THE EDITORS 

 OF THE AMERICAN JOURNAL OF SCIENCE AND ARTS. 



Gentlemen, In the Twelfth Annual Report of the Regents of the University* upon the State Cabinet of 

 Natural History, I published descriptions of three species of trilobites from the shales of the town of Geor- 

 gia, in Vermont, referring them to the age of the Hudson River group. These trilobites had been in my 

 possession for some two years or more; and knowing the great interest that would attach to them, when- 

 ever published, I had waited, hoping that some new facts might be brought out touching the stratigraphical 

 relations of these rocks in the town of Georgia. 



After the descriptions had been printed and a few copies distributed, I learned that Sir William Logan 

 was at that time actually investigating the rocks of that part of Vermont. Desiring to know the results of 

 his latest researches in regard to the stratigraphical relations of these rocks, I withheld the final publication 

 till the meeting of the American Association for the Advancement of Science, in Springfield, and there 

 showed to Sir William my descriptions as they now stand in the Report, and I then received his authority 

 for the addition of the note which was appended. 



This in a few words is a simple history of the matter relating to the publication of these species. I 

 made no remarks or comparisons with the primordial fauna of Barrande in Bohemia, knowing that these 

 features would be at once recognized by every palaeontologist; while their reference to the genus Olcnus 

 showed my appreciation of the nature of the fossils. 



I received a copy of the communication of Mr. Barrande, from Sir William Logan in September, a 

 few days before setting out for my fjeld duties in Wisconsin. Since my return to Albany, constant and 

 pressing occupation has left me no time to consider a reply to a question of so much importance. 



Later discoveries in the limestones associated with the shales at Quebec, leave no longer a doubt, if any 

 could have been entertained before, that the shales of Georgia, Vermont, are in the same relative position; 

 and we must regard these trilobites as .belonging to the same fauna with the species enumerated by Sir 

 William Logan as occurring in the Quebec group. Left to paheontological evidence alone, there could 

 never have been a question of the relations of these trilobites, which would at once have been referred to 

 the primordial types of Barrande. 



* The same to which Mr. BarranJe refers in his text to Prof. Bronn, p. 312. The preceding communications sufficiently explain the 

 subject under discussion. 



