and the Paleozoic System of England, 361 



other a similar succession of organic types, and each might have 

 its appropriate nomenclature. Nature has been so true to her 

 workmanship, that the two would, with a very few exceptions, 

 run harmoniously together. But in the actual state of our 

 information, we have done well constantly to use both kinds of 

 evidence ; and on both together has our best, and our only 

 consistent and secure, nomenclature been founded. If it be 

 true that experienced geologists have sometimes, from the 

 neglect of palseontology, blundered in the arrangement of phy- 

 sical groups, it is equally true, that very expert palaeontologists, 

 from some mistake of arrangement among the physical groups, 

 have sometimes blundered in their palaeontology. The double 

 kind of evidence above described^ has seldom been lost sight of 

 with impunity. 



We have, within a few years, had an excellent illustration of 

 the combined value of physical and fossil evidence, in the defini- 

 tion of our oldest tertiary groups, and in the determination of 

 their nomenclature by Mr. Prestwich ; and principles precisely 

 similar have led to a good geographical nomenclature of the 

 great subdivisions of our whole palaeozoic system. So far as 

 our palaeozoic nomenclature is good, and fitted to endure, it has 

 been grounded both on physical and palaeontological evidence. 

 So far as it is inadequate or erroneous, it has either been derived 

 from sections which were misinterpreted, or from a positive de- 

 sertion of those principles of combined evidence on which all 

 the good and enduring parts of our palaeozoic nomenclature are 

 grounded. 



From the same combined principles of evidence, I have given 

 (in the following corrected tabular view) what I believe a true 

 geographical nomenclature of the oldest palaeozoic groups. It 

 may not be the most scientific (and may hereafter be superseded 

 by something better) ; but it is a nomenclature, I believe, best 

 suited to the present condition of our knowledge ; and it exactly 

 falls in with all those groups which have, on the same principles, 

 been well established in the ' Silurian System .'' In every case 

 where this kind of nomenclature has led to a geographical in- 

 congruity, we may rest assured that such incongruity is not the 

 fault of nature^s workmanship, but has sprung from some mis- 

 application of our principles of classification, or some great 

 mistake in our assumed position of the physical groups. 



Phil Mag. S. 4. Vol. 8. No. 53. Nov. 1854. 2 B 



