1 1 The Cambrian and 



been misled himself, or misled others, in giving wrong names and 

 wrong British equivalents to distant regions, such mistakes belong 

 not to the fundamental questions discussed in this reply. I have 

 looked only to facts and first principles, and fiat justitia, without 

 regard to my own mistakes or those of others, shall be my motto. 

 And I reaffirm that no authority on earth can make the lower 

 Silurian sections right, or subordinate to them the great Cambrian 

 series. 



Had I space for the discussion, I could prove that several of 

 the authorities quoted against me do, when rightly interpreted, 

 make good weight of evidence on my side ; and I have not the 

 shadow of a doubt that my own scheme of classification will bring 

 the older British palaeozoic groups into far better co-ordination 

 with the magnificent palaeozoic series of America than they have 

 ever been brought before, through the intervention of the imper- 

 fect, and (so far as regards the lower groups) the erroneous sec- 

 tions of the Silurian system. The comparison of foreign palaeo- 

 zoic rocks with those of Britain has hitherto, I affirm, not been 

 based " upon a natural British arrangement " but upon an arrange- 

 ment partly defective and partly erroneous, and therefore unna- 

 tural. The establishment of a better nomenclature, based upon 

 better sections, will give foreign geologists better terms of com- 

 parison, and thereby clear away many existing mistakes, and much 

 present confusion. Harmony and order will inevitably follow the 

 establishment of a true typical palaeozoic series in England ; and 

 the points at issue between my friend and myself by no means 

 are dependent upon any future questions which may arise re- 

 specting certain changes in the palaeozoic names and colours of 

 foreign maps, provided my scheme of classification and nomencla- 

 ture were adopted. The only questions admissible in the debate 

 are those which have a bearing on the truth of the sections, the 

 natural succession of the groups, and the geographical propriety 

 of the collective names when applied to British rocks. With the 

 assertion of this principle of common sense I conclude my reply. 



Adam Sedgwick. 



2. Sir R. I. Murchison's Comments on Professor Sedgwick's 

 Letter {No. 1.) 



April 17. 



The letter of my old friend Professor Sedgwick, has not, it ap- 

 pears to me, at all affected the integrity of the Silurian System, as de- 

 fined by myself many years ago, and as since understood and received 

 by geologists. A very brief review of data which my friend seems 

 to have forgotten, is alone required. It is beside the question now at 

 issue to revert to what we respectively did in the field in 1831 and 



