Ixxvi INTRODUCTION. 
Flag determined. There is no escape from this conclusion; for if we reject it, our nomen- 
clature is nothing better than a verbal cheat. But by a great geological mistake the 
flag of Llandeilo was put in a false relation to my Upper Cambrian group. Therefore 
when the “Silurian System” was published, the author must have so misinterpreted the 
Montgomeryshire sections as to put the Llandeilo Flag of that county also in a false relation 
to the Upper Cambrian group. ‘That he did so, there can be no doubt. And it is, I 
think, plain that he continued in this error in 1841, when Dr Fitton’s Review of the “Silu- 
rian System” was published. He may, during that year, have had some glimmering of his 
own great mistake; and he may afterwards have made a second mistake in supposing that 
my Welsh sections were erroneous in principle*. He knew after 1834 that the fossils of 
the Bala group, so far as they were known, were identical in species with those of his 
Lower Silurian groups. I had myself published the fact two years, or more, before the 
appearance of the “Silurian System;” and I published a corresponding fact respecting the 
Snowdonian fossils before I revisited North Wales in 1842. At that time my friend believed 
(by a positive mistake of his own) that I placed the fossils of the Snowdonian trough 
near the base of the whole Cambrian Seriest. Hence he believed that the fossils of the 
whole Cambrian Series were nothing more or less than fossils of his two lower Silurian 
groups. His whole logic (if that may be called logic which was an abandonment of his own 
principles of classification) was perfectly transparent. His own fundamental and typical sections 
were wrong; but what of that? the fossil lists were right: and by developing the Llandeilo 
Flag upwards through five or six thousand feet of strata, and downwards through more than 
twenty thousand feet of strata—in short, by absorbing Cambria into Siluria—his scheme 
of nomenclature would stand good upon palzontological grounds alone. That this was the 
scheme, and the logic by which it was worked out when the Silurian map was changed 
in 1843, I have not the shadow of a doubt. It was publicly avowed and vindicated. 
What right, then, has my opponent to bring forward the Montgomery sections with a 
view of insinuating a fundamental mistake on my part, when I had, in fact, made no mis- 
take whatsoever? Up to 1848, and a later period, he misunderstood the Montgomery sections ; 
as is indeed certain from his own nomenclature. And when the controversy began about 
ten years since, if he had discerned the least glimmering of light, from @ new interpretation 
of the Montgomery sections, he would not have failed to turn it to his own account. I 
contend, therefore, that in the above quotation my friend has historically mystified the 
whole subject, by keeping out of sight his original types, and his original grounds of evidence; 
* IT believe that my friend was led into some error by Mr Sharpe's sections, who first wished to make the Bala 
group into the equivalent of the Caradoc sandstone. Afterwards Mr Sharpe gave a still newer date to the Arenig por- 
phyries ; and by the interpolation of supposed faults, made the rocks near the Menai Upper Silurian! If the author of 
the Silurian System accepted any part of these very erroneous views, he must have suspected that my Cambrian sections 
were all constructed on a mistaken principle. That he was misled is certain; and after 1834 he had no communication 
with myself respecting any of the Welsh sections. 
+ See Siluria, end of first paragraph, p. 9. 
