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species of Cephalaspis, or Pteraspis, belongs of right to the Silurian system, 

 and will have to be detached from the true Old Red. What you say and what 

 Geikie says of the break between the Upper and Lower Old Red (so called) of 

 Scotland, is an argument in favour of this idea, that Lower Old Red is a 

 Silurian sub-group. I think it very likely that two or three formations (systems, 

 or series, some perhaps not known anywhere yet) are represented in our country 

 by that jumble of red sandstones, conglomerates, etc., etc., which have been 

 hitherto confounded as Old Red. I believe the Lower Old Red to be upper- 

 most Silurian, and the uppermost Old Red to be lowermost Carboniferous. 

 Whether anything that might be called Devonian will come anywhere between 

 them is an unsolved problem. But neither the Lower Old Red nor the upper- 

 most Old Red are entitled to be called Devonian, unless by Devonian you 

 mean a sub-group of the Carboniferous. 



I still doubt your fault, and your supposition of trap coming up it makes me 

 doubt it more. I have heard of such cases, but I never saw one, and doubt 

 the intrusion of igneous rock being ever connected with disturbance. 



That, however, is mere doubt ; but I am sure it only misleads to class under 

 one name two groups which are unconformable to each other. 



I tell you this in order that you may keep your eyes open and not commit 

 yourself too far in favour of old notions that will shortly be consigned to Limbo, 



Mrs. Jukes unites in kind regards to yourself and your sister. 



Yours very truly, 



J. BEETE JUKES. 



Then follows a paper that I had occasion just now incidentally 

 to allude to. For some time past Harkness had been going again 

 and again over the ground described by Sedgwick in his well-known 

 paper on the New Red of these parts. With the rapid advance 

 that was then being made in the geology of the older rocks — an 

 advance that was due very largely to Murchison's orderly conspectus 

 of the facts collected by every worker at the subject, Harkness 

 himself amongst others — it was hardly possible for Harkness not 

 to be fully aware that a very great deal yet remained to be worked 

 out before the sequence of the Edenside Red Rocks could be 

 reduced to anything like a definite system or order. And this was 

 the task he next addressed himself to. To us now-a-days, the real 

 difficulty of this undertaking can hardly be fully estimated, unless 

 it be by anyone that would undertake to begin the work with the 

 same amount of information to start with that he had. It must be 

 borne in mind, if we would be just in our appreciation of the true 



