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so unwell. Sir E. presented me with the prize Survey Silurian Medal, and 

 had written in the inside of the box containing it : "To my valued friend 

 Thomas Davidson, in memoriam of his admirable illustrations and History 

 of Silurian Life, Sept. 25, 1868. (Signed) Rod. I. Murchison." It is a 

 beautiful medal, and the likeness of Sir Roderick on one side is admirable. 



* * We have been intimately acquainted for more than thirty years, 

 and all along be has shewn me the greatest kindness and desire to see me 

 rise in the esteem of geologists and men of science. 



He also spoke in the most flattering terms of your valuable researches. 



* * I told him how kindly you had assisted me, which seemed to please 

 him. He told me also that he had expressed a desire that every possible 

 assistance should be afforded me by the Survey, as he considered my larger 

 work as one of very great importance to the Survey. 



In a letter I have just received he again says * * " Harkness has done 

 much good in elaborating the order and contents of these older rocks." 



I had a long conversation with Sir Roderick with reference to Hicks* 

 proposal to remove the Lower Lingula Flags (Menevian) from his primordial 

 Silurian, and to add them on to Sedgwick's Lower Cambrian, or Harlech 

 Beds. But Sir R. considers (like Barrande and De Verueuil) this his Lower 

 Lingula Flags constitute the base of his lowest Silurian or Primordial 

 Silurian, and that if the Harlech Group, or Upper Longmynd, is found to 

 contain the same forms as his Lower Lingula Flags, this would shew that 

 this Primordial Silurian should be carried a little lower down. I confess to 

 you that I have never thought that there existed two Natural History 

 Systems, viz., a Cambrian one and a Silurian. In my ideas the whole 

 of the strata from the Harlech group up to the uppermost Ludlow 

 would form one great system, by whatever name you may choose to 

 call it — Cambrian or Silurian. However, if Hicks can shew good 

 cause why there should be two Natural History Systems in that series 

 of Older Palaeozoic rocks, I shall be glad to recognize the matter ; but such 

 can be done only after Mr. Hicks shall have figured and described the 

 Harlech and Menevian fossils. When in Paris I am going to have a long 

 chat with M. De Verneuil upon this and several other impoi-tant matters, 

 some of which Sir Roderick wishes me to carefully investigate. I find that 

 •generally speaking foreign geologists are not more convinced than I am 

 myself of the validity of the Cambrian and Silurian Natural History 

 Systems. We all know that a certain number of genera in every large 

 system of rocks are restricted to certain portions of this system. 



Hicks's researches and discoveries are of the greatest value and import- 

 ance, and no small praise is due to him for the very able and persevering 

 manner In which he has worked. I shall therefore look forward with the 

 greatest impatience to the publication of his valuable paper upon those very 



