34 Mr R. I. Mnrchison on the Discovery 



give you a more decided opinion than I was then enahled to do, re- 

 specting the age of the lowest and oldest of the sedimentary rocks of 

 Cornwall. 



Not having seen the fossils collected by Mr Peach on the south 

 coast of Cornwall, I then found it difficult to come to any other con- 

 clusion than that at which Pi'ofessor Sedgwick and myself had long 

 ago arrived ; viz., that, with the exception of the presence, in the 

 north-eastern extremity of the country, of a portion of the culmifer- 

 ous (carboniferous) trough of central Devon, the remaining and un- 

 derlying strata of Cornwall were of the age of the Devonian or old 

 Red system. The few Cornish fossils which were then shewn to me 

 in your museum, were unquestionably similar to those with which I 

 was formerly familiar in Devonshire and North Cornwall, as well as 

 with those of the Rhenish provinces and the Eifel, which Professor 

 Sedgwick and myself had shewn to occupy a like geological position. 

 They were in fact, forms of the same type as those which, at the 

 suggestion of Mr Lonsdale, and with the assistance of Mr James 

 Sowerby on one occasion,* and with the help of MM. do Verneuil 

 and d'Archiac on anothcr,t we had published as characteristic of a 

 group of intermediate characters, pertaining to strata lying beneath 

 the carboniferous rocks and above the Silurian system. In a word, 

 they were identical with some of the numerous fossils of Devon and 

 North Cornwall, published in the work of Professor Phillips \\ who, 

 in pointing out in certain tracts the connection of this group with the 

 carboniferous fossils, which he had so well described, and in others 

 with the Silurian forms I had published, had also concluded that the 

 great mass of fossiliferous strata which rise up from beneath the culm 

 measures of central Devon were of the same intermediate characters. 

 In his valuable maps of Cornwall and Devon, Sir H. de la Beche 

 gave essentially the same views of geological succession ; and, lastly, 

 in his report upon the geological structure of that region, he described 

 certain detailed sections in the southern districts of Cornwall, to which 

 I will presently advert. 



In proposing the word " Devonian," as applied to the intermediate 

 strata in question, Professor Sedgwick and myself thus qualified our 

 meaning in regard to the extension of such rocks into Cornwall : — 

 '• In asserting that the stratified rocks of Devonshire and Cornwall 

 are, upon a broad scale, the equivalents of the carboniferous and old 

 red systems, we do not however deny, that, in certain tracts, the 

 lowest members of some of these rocks may represent the upper di- 

 vision of the Silurian system ; for although we have as yet found few 

 if any of the fossils most typical of that system, we admit that when 

 the sediments of a given epoch have been accumulated under peculiar 



* Trans. Geol. Soc, N.S., vol. v., p. 633. 



t Idem, vol. vi., pp. 221, 303. 



1 Palaeozoic Fossils of Devon and Cornwall. 



