and the Palceozoic System of England, 367 



clature is right, because it has the unquestionable right of 

 priority, — because it is geographically true — and because it is 

 also palseontologically true. On the contrary, the scheme by 

 which it has been opposed is an innovation, without being an 

 improvement derived from progressive evidence. It has been 

 vindicated only by a direct desertion of the system of double 

 evidence on which the true Silurian groups were firmly esta- 

 blished. Hence it is geographically untrue, and it is palaeonto- 

 logically erroneous*. 



So long as geologists believed in the existence of a so-called 

 "Middle Silurian Group,^^ there was unquestionably a great 

 palseontological diificulty ; and there was a show of reason for 

 affirming that all the rocks of the Lower Palaeozoic division 

 were of one palaeozoic system, and must therefore have one 

 name, and might therefore be called " Silurian." But we 

 have no right to mask a difficulty by a mere name. If the 

 difficulty had existed (though, in point of fact, the very dif- 

 ficulty arose out of a palpable mistake), it would not have 

 proved the Cambrian groups to be Silurian, but it would have 

 proved that the Silurian groups had no base ; and therefore, 

 from the first, had been erroneously described as a system. If 

 we rank all the Silurian groups as one Silurian system, we 

 establish our upper groups fairly, upon a double scheme of 

 evidence, derived from true physical groups and their correspon- 

 ding groups of fossils. But we cannot carry the scheme down- 

 wards, below the May Hill sandstone, without a positive desertion 

 of our former scheme of evidence. No wonder that a nomen- 

 clature derived from such inconsistency of evidence and change 

 of principle, should lead to a glaring geographical incongruity. 

 Its introduction ought never to have been attempted. 



But, after all, the supposed difficulty does not exist. Strike 

 the May Hill sandstone from this so-called Middle Silurian 

 group, and we at length obtain a true physical and palseonto- 

 logical base for the Silurian groups. Why it remained so long 

 undiscovered I do not inquire; but the fact does prove the great 

 hindrance to good classification and real progress which arises 

 out of the premature adoption of definite scientific names. 



* In his last published scheme of nomenclature. Sir R. I. Murchison 

 classes all the stratified rocks of Wales which are below the Wenlock shale, 

 under the name " Llandeilo formation ; " which appears to me nothing less 

 than a downright reductio ad absurdum. There is, in the Llandeilo country, 

 no type, or semblance of a type, of the older palaeozoic groups of the 

 Cambrian Mountains. What is the Llandeilo flag ? Certainly a remark- 

 able fossihferous group (about the age of the Bala limestone), of which the 

 geological place was entirely mistaken in the " published " sections of the 

 ' Silurian System/ As a type for palseozoic nomenclature it is, therefore, 

 worse than nothing. . 



