Silurian Discussion concluded. 109 



Silurian species were removed, it was plain that we had no right 

 to look for, nor did I ever expect to find, any great succession of 

 changing organic types in the vast series below the Caradoc sand- 

 stone. But we have no right to name this vast series from a 

 single group near its upper surface. My names are geographically 

 true, and from the first were honestly derived from sections tra- 

 versing the series from top to bottom. My friend stopped short, 

 or mistook his way, in the descending series, and then ventured 

 to blot out the old and true name, and to give his own name to a 

 great series he had not explored, thereby violating a principle 

 which teaches us that systems and groups must be established 

 first, and that names must follow afterwards. 



In another sentence of his comment, my friend tells me " that 

 these observers (viz. Sir H. de la Beche and the other gentlemen of 

 the Government Survey) have satisfied themselves that the region 

 called Cambria, at a time when none of its fossils were described, 

 is made up of the same strata, and contains the same organic re- 

 mains, as the lower Silurian rocks," &c. &c. It is not correct to 

 say that none of the Cambrian fossils had been described ; but I 

 will let that mistake pass, as a small matter in comparison of the 

 enormous misstatements (to be explained only by the incautious 

 hurry of my friend's comment) that the older Cambrian groups are 

 made up of the same strata, and contain the same organic remains 

 as the lower Silurian rocks ! I would venture to stake my life 

 upon the issue of a question as to the correctness of this assertion. 

 I will give my friend a descending point two or three thousand 

 feet below any rocks he has reached in any true section, and the 

 gentlemen of the Survey will tell him that he may descend 20,000 

 feet lower still before he reaches the lowest limit of organic life as 

 seen among the older groups of Wales. 



That the Government surveyors have adopted my friend's 

 nomenclature is true. But I believe that the director of the Sur- 

 vey adopted it, not because he thought it best and most true to 

 nature, but because he believed "that I had given up a very good 

 nomenclature.'" I believe he was led into this mistake by a map 

 (first Number of the Journal of the Geological Society, p. 22), 

 which was introduced by myself, but not submitted to my revision, 

 and which, in the explanation of the colours, utterly misrepresents 

 the meaning of my paper, and of which I therefore disclaim the 

 authorship. Be this as it may, no authority upon earth can 

 make the adopted nomenclature either historically just or geo- 

 graphically true. 



I cannot follow my friend in his excursions to distant lands. 

 The question between us is a question only of the classifica- 

 tion of British rocks, and must be decided only on British evi- 

 dence. If* he, in a rash zeal for a premature nomenclature, has 



