Silurian Discussion. 117 



tion, at least 25,000 feet to its base. The Llandeilo flag, thus 

 developed and tricked out, becomes the equivalent of my Cambrian 

 system ! But under no interpretation, compatible with the plain 

 meaning of words, can it be called " the original published Siluria 

 of Murchison." 



5. I re-affirm, with great confidence, that my friend has utterly 

 shifted his original ground of classification. In his reply to my 

 remarks on this head, lie has kept out of sight the important fact, 

 that in 1834 (the last time we were together in North Wales) he 

 accepted my interpretation of tbe Bala limestone ; and, spite of 

 its fossils, declared his conviction that, by the evidence of the sec- 

 tions, it was unequivocally a member of the Cambrian series, and 

 removed it out of his Silurian system. If he afterwards saw reason 

 to change his views as to this essential point, he was, I think, 

 called upon to communicate that change to myself; but no such 

 communication was ever made to me. Again, it is by no means 

 correct to say that the Cambrian rocks were undefined, and their 

 fossils unknown. The rocks were well defined by true sections. 

 No good general list of their fossils had been published by myself ; 

 but I stated, again and again, before the publication of the Silurian 

 system, that many of the Cambrian fossils were of identical species 

 with the Lower Silurian ; that in the Bala group several fossils 

 (enumerated by their specific names), and nine species of Orthis, 

 were identical with known Lower Silurian species, &c. &c. Lastly, 

 my friend himself, though he called the Bala limestone Cambrian, 

 did not discover in it a single species that was not also found in 

 the Llandeilo group. When he afterwards, discarding the evidence 

 of sections, began to feel his way downwards, and, by help of 

 fossils only, endeavoured to bring the great Cambrian groups 

 within the narrow limits of his two Lower Silurian stages, I have 

 a right to affirm that he shifted his ground, and deserted the ori- 

 ginal principles of his classification. 



6. Speaking of himself and Count Keyserling, he informs us — 

 " that in 1842 they satisfied themselves that, after many apparent 

 flexures, strata containing the same fossils appeared on the flanks 

 and summit of Snowdon as those they had left on the east flank 

 of the Berwyns, a country which had been specially mapped and 

 described as Silurian." As to the country east of the Berwyns, 

 a part of it was erroneously mapped by my friend, and another 

 part of it was erroneously coloured by myself, in conformity with 

 his misinterpretation of the deposits, which he made Caradoc sand- 

 stone. To have been consistent, therefore, he and Count Keyser- 

 ling must have regarded the top of Snowdon as Caradoc sandstone, 

 a conclusion which would have been incontestably erroneous. As 

 to the Snowdonian fossils, I had published a pretty good list of 

 them at least twelve months before the summer of 1842, and a 

 short list had been previously given by Professor Phillips. They 



