S20 TKE CANADIAN NATURALIST^ [Yol. Yl. 



gist worked at the problem. I conducted the palaeontology 

 throughout. Sir W. E. Logan's final decision was &iven on the 

 last day of December, 1860, and from that date no one has referred 

 either the Taconic or the Quebec rocks to the Hudson River 

 group. 



The Canadian Survey did not originate the Taconic theory, 

 but it exposed and removed from American geology, the enorm- 

 ous error which placed the rocks at the summit of the Lower 

 Silurian. The palaeontologists who were consulted by me were, 

 Barrande, Salter, Shumard and Safford. as above mentioned. The 

 others who have made important discoveries bearing upon the 

 subject are the following. 



In 1861 Mr. J. Richardson of the Canadian Survey, discover- 

 ed the Vermont trilobites, at the Straits of Belle Isle and at 

 Bonne Bay, in Newfoundland, in rocks which lie below that part 

 of the Potsdam which holds Lingula acumiriata. 



In the same year the Rev. J. B Perry and Dr. Gr. M. Hall 

 discovered a new locality of the trilobites, about IJ miles east of 

 Swanton in Vermont. 



Mr. T. C. Weston, of our Survey, collected a nearly perfect 

 head of a species of the same genus at Bald Mountain in New 

 York, in June, 1864. 



In July, 1871, Mr. S. W. Ford of Troy, New York, published a 

 short paper in the Am. Jour. Sci., entitled : " Notes on the pri- 

 mordial rocks in the vicinity of Troy, N. Y." This paper was 

 l-e-published iti the Can. Nat. in December 1872. Mr. Ford gave a 

 g:ood description of the rOcks of the locality, and announced the 

 discovery of 18 species of fossils, 15 of which were found on com- 

 parison to belong to the Taconic fauna. Mr. Ford's paper, with 

 the exception of what Dr. Emmons himself had written, is the 

 most important that has ever been published in the United States 

 on this subject; It consists entirely of original observations, while 

 a large number of the papers that have appeared in the scientific 

 journals, relating to the Taconic rocks, are mere compilations, in 

 which the question is misrepresented, many important f..cts sup- 

 pressed, and others presented in a false light. 



3. — Determination of the age of the Red Sandrock of 



Vermont. 

 Intimately connected with the Taconic question, is the deter^ 

 mination of the Red Sandrock formation of Vermont. This 



