MURCHISON ON THE SILURIAN SYSTEM. 177 



three species of which only are mentioned, not one being figured), I 

 refer to his own words*. 



At the same time there came out (for the work was really issued 

 in 1838, though 1839 is on the title-page) my ' Silurian System' with 

 its detailed evidences and figures, by which, both at home and abroad, 

 so many regions have been assimilated to the Lower as well as to 

 the Upper Silurian tracts therein described. So far for the priority 

 of our respective publications and for the nature of them. 



I had, in a word, completed in 1 838 the illustration of a natural 

 system which had been worked out by fossil evidences in 1833, 1834, 

 and 1835, whilst in the same years Professor Sedgwick had neither 

 shown the real physical relations of his rocks to my already well- 

 known types, nor had he published any descriptions of fossils by 

 which his so-called '' Cambrian System" could be recognized as enti- 

 tled to a separate name. 



(1840-43.) Unwilling to encroach upon the Cambrian region, and 

 believing, from the delay of my friend (his fossils were even then 

 unexamined), that much time must elapse before the rocks of so 

 complicated, contorted, and difficult a country as North Wales could 

 be properly classified, I resolved to test the value of my own labours 

 by an extensive appeal to foreign countries, and in consequence visited 

 Russia accompanied by M. de Verneuil in 1840 and 1841, where 

 Count Keyserling joined us. The results were so palpable, that, 

 being again President of this Society, I put forth, in the most pro- 

 minent and public manner in the first pages of the Discourses of 

 1842 and 1843, as printed in the Proceedingsf, the expression of 

 my conviction, that the Lower Silurian rocks were the oldest fossil- 

 bearing group ; adding my belief that the same rocks ranged over 

 nearly all North Wales. 



I specially refer every student in geology, who may not have fol- 

 lowed the process of induction by which the Silurian classification 

 was thus applied generally, to the pages of my Discourse of 1842 

 which commence under the heading of * Palaeozoic Geology,' and in 

 which the Silurian, as surmounted by the Devonian and Carboniferous, 

 is shown to be the oldest fossiliferous system J. My general view was 

 founded on what I saw in the north of Europe and in Bohemia, 

 and my distinct and final application of it to North Wales was made 

 in 1 843 in consequence of a traverse across that region with Count 

 Keyserling, when we found the Lower Silurian fossils in and around 

 Snowdon. Hence the publication of my small general Map of Eng- 

 land, executed at the request of the Society of Useful Knowledge, in 

 which the erroneous line of demarcation between Siluria and Cam- 

 bria was obliterated. 



In these proceedings, which, in a British geographical sense, so 

 vastly extended the application of the Silurian system, and which 

 showed why the provisional cartographical boundary between Siluria 

 and Cambria was expunged, I simply but courteously explained, that 

 a broad appeal to nature in foreign countries, followed by a traverse 



* Op. ciL p. 554. t Vols. iii. and iv. 



t Proceed. Geol. Soc. vol. iii. p. 640. , 



