INTRODUCTION. Ixxiil 
which rose up, according to my friend and fellow-labourer, from beneath my Silurian 
Types. ence, another term, that of Cambrian, was afterwards, in 1836, applied to masses 
that were supposed to be inferior, before the true relations to the Silurian strata of Shrop- 
shire had been ascertained. This assumed inferiority of position, in the slate-rocks of 
North Wales, being considered a fixed point, it was naturally thought that in such lower 
formations, the fossils of which were then undescribed, would be found to contain a set of 
organic remains differing as a whole from my classified and published ‘Silurian System.’ 
With other geologists, therefore, | waited for the production of the fossils which might 
typify such supposed older sediments.”...... “It was, however, in vain that we looked for a 
peculiar type of life from the ‘Cambrian’ rocks. Silurian fossils alone were found in them ; 
and the reason has since become manifest. The labours of many competent observers, in 
the last fifteen years, have proved that these rocks are not inferior in position, as they 
mere supposed to be, to the lowest stratified rocks of my Silurian region of Shropshire and 
the adjacent parts of Montgomeryshire, but are merely extensions of the same strata...... 
and that the fossil-bearing rocks of North Wales are both in their order and contents the 
absolute equivalents of the chief mass of strata which had been described and named by 
me ‘Lower Silurian’ in Shropshire and Montgomeryshire...... Although in 1839 I held 7 
common with Professor Sedgwick the erroneous idea of the infra-Silurian position of the 
rocks of North Wales, I soon saw reason to abandon that view, and to adopt (in the year 
1841) the opinion I have subsequently maintained.” 
I do not mean to misrepresent the author by garbled extracts. It is both my interest 
and my duty not to misrepresent him. Are these extracts a true philosophical history of 
facts and inferences? They are not history, but sheer advocacy: and very bad advocacy, 
because they blink some essential facts, draw the reader away from the first Silurian types 
on which the whole nomenclature rested, and inevitably lead him (if he be not better 
informed) into conclusions respecting myself which are positively untrue. 
In the first place, in alluding to the old slate-rocks of North Wales, he tells us, 
that according to my friend and fellow-labourer they rose up from beneath my Silurian 
iypes. What is this but virtually to repeat, and turn to profit, the very erroneous state- 
ment of Mr Sharpe, which I have already discussed? Sir R. I. Murchison (when President 
in 1848) ought to have corrected the misstatement; and in failing to do so, he failed, I 
think, in a duty he owed to plain historic truth. And if he failed somewhat in 1843, 
much more does he fail in 1854, if in the words I have quoted, he means most remotely 
to insinuate that I misled him in his mistaken views as to the relation of his Lower Silurian 
groups to my Upper Bala group, or generally to the slate-rocks of North Wales. If this 
he his meaning he is either under some strange delusion arising out of his one-sided earnest- 
ness to establish his own System; or, having claimed a despotic title to all older Paleozoic 
rocks, he may think that he has a right to claim a royal privilege, and that “he can do 
no wrong,” while he is dealing with his own subjects. Science is a republic that admits 
no such plea. I declare, with the earnestness and sincerity of plain straightforward truth, 
k 
