Basin of the Eden and north-western Coasts of Cumberland, ^c. 403 



ferous formations of Fifeshire. 1 coiiclude^thereforejlhat the true position of the 

 ichthyolites of Caithness is out of all doubt, and adhere, with very sHght modi- 

 fications, to the classification published by Mr. Murchison and myself*. 



By way of conclusion, I may add, that the anomalies at which I have 

 pointed, in different parts of this paper, and the difficulties they throw in 

 the way of any universal classification, can be no matter of surprise. The 

 great cause for wonder is, that among such vast and rude, mechanical 

 operations of nature, we should be able to trace even the approximate ele- 

 ments of order. Whatever may be hereafter decided about the general group- 

 ing of the coal measures, the near coincidence of even the minute minera- 

 logical subdivisions of the new red sandstone series in the North of England 

 and central Germany, and the general correspondence of their fossils, must be 

 regarded as one of the most satisfactory conclusions of secondary geology. 



POSTSCRIPT. 



Cambridge, August 7, 1835. 



In consequence of the long delay in printing our Transactions, memoirs 

 must sometimes appear whiclr, at the time of their publication, do not express 

 correctly the opinions of the respective authors. The preceding paper is 

 published (with the exception of verbal corrections and the addition of the 

 short notes) as it was read to the Society. Had the concluding remarks been 

 written now, they would have been considerably modified. 



I have taken for granted that the Exeter conglomerates, and those over- 

 lying our south-western coal fields, are of the same age. Mr. De la Beche 

 has, I believe, ascertained, since this paper was read, that the former are older 

 than the latter. Hence, the remarks intended to show that the magnesian 

 conglomerates (e, g-. those of the Bristol coal fields, the flanks of the Mendip 

 Hills, &c,) were not the equivalents of the rothe todte liegende, cannot be 

 applied to the conglomerates of Exeter, at least without some modification. 

 The Exeter conglomerates may, then, be equivalents of the upper part of that 

 sandstone which, in the North of England, fills up the chasm between the coal 

 measures and the group of the new red sandstone. There is, however, in all the 

 sections of Somersetshire, Devonshire, and South Wales, a want of continuity in 

 these formations. Their position is perfectly discordant, so that it is physically 

 impossible the successive deposits should be complete : something is wanting, 

 which is supplied by the uninterrupted sections in the North of Englandf. 



* Geological Transactions, Second Series, vol. iii. p. 157. 



f Precisely in the same way, the sections in the North of England, connecting the old red sand- 

 stone and the slate rocks, are not continuous ; and there is just the same break in Denbighshire 

 VOL. IV. SECOND SERIES. 3 G 



