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XL VI. On the May Hill Sandstone, and the Palaosoic System of 

 England. By the Rev. Prof. Adam Sedgwick, FM.S., F.G.S. 



[Concluded from p. 317.] 



Tabular View and Nomenclature of the British Palaeozoic 

 System, ^c. 



AS a sequel to the previous details, I subjoin the following 

 remarks on the classification and nomenclature of the 

 British palaeozoic rocks. The triple division of our whole series 

 of fossil-bearing rocks into primary, secondary, and tertiary, 

 may still be conveniently retained; and. when these three divi- 

 sions are described with reference to their organic types, they 

 have been respectively defined by the terms palceozoic, mesozoic, 

 and ccenozoic. To each of the three great divisions I would, on 

 palgeontological grounds, give the name of System, Thus, in 

 the following corrected tabular view, all the palaeozoic rocks, 

 from the oldest Cambrian to the Permian inclusive, are described 

 as forming parts of one system — the Palaeozoic. This extended 

 application of the word system is an innovation on a nomencla- 

 ture now in common use; but it was suggested by myself 

 fourteen years since, for the express purpose of avoiding what I 

 thought an unphilosophical use of the word system, as applied 

 to the subdivisions of the palaeozoic rocks — such as Carboniferous, 

 Devonian, Silurian, &c. ; and since then I have repeatedly used 

 the word system in this extended sense, and recommended its 

 adoption*. Strictly speaking, all organic types, of whatever 

 date, belong to one great Systema Naturae. Had this not been 

 true, palaeontology could never have risen into a science. Still 

 there is such a great organic interval between the flora and 

 fauna of the primary and secondary groups, that we may con- 

 veniently, and without any risk of error, describe each of them 

 as belonging to a separate organic system. A single glance 

 convinces us that the fauna of the secondary period greatly 

 differs from that of the primary or palaeozoic. But the case is 

 widely different in comparing the organic types of the subdivi- 

 sions of the palaeozoic rocks. Both physically and palaeonto- 

 logically, we find a great difficulty in drawing fixed lines between 

 these subdivisions; nor at this moment are geologists in all 

 cases agreed as to the true places where such lines should be 

 drawn. 



Not only have all the palaeozoic rocks a peculiar organic type, 

 but there are several species which run through nearly all the 

 subordinate groups, and seem, therefore, to unite them into 



* For example. Proceedings of the Geological Society, vol. iv. June, 

 1843, p. 221. 



