and the Palceozoic System of England. 369 



used in a definite sense, and be applied to the successive divi- 

 sions of the palaeozoic rocks, such as the Devonian/^ (Proceed- 

 ings of the Geological Society, vol. iv. p. 224.) 



Let no one suppose that 1 undervalue the importance of the 

 great fossil lists derived from the Caradoc and Llandeilo groups. 

 Their palaontological value remains unchanged, whatever be the 

 nomenclature and ultimate arrangement of these groups. But 

 I may add, that such fossils have comparatively small geological 

 value before their real sectional position (in the general sequence 

 of our palaeozoic rocks) has been determined; and, until that 

 point has been cleared, they are of no value in helping us to a 

 true nomenclature of our palaeozoic groups. Many years before 

 I ever set my foot in Wales, and before the * Silurian System^ was 

 thought of, the Asaphus Buchii and other species were known 

 as characteristic of the flags of Builth and Llandeilo. Some of 

 the species (then unnamed) from Snowdon, Meifod, Coniston, 

 &c. were not unfamiliar to collectors ; and very beautiful col- 

 lections from the Silurian groups (especially the Wenlock) had 

 been made, and some of the species had been published. But 

 this knowledge, even had it been ten times greater than it was, 

 could give no help to the advancement of palaeozoic geology, 

 until the position of the fossil-bearing groups had been ap- 

 proximately determined. So far as this task was done in Siluria, 

 the ' Silurian System,^ and its geographical nomenclature, 

 stands good ; and in the preceding Tabular View the author of 

 that " System " is not deprived of one single group of which the 

 true place was determined in his published sections. ''-"■ 



If all the colours of the Silurian Map were laid down in agree- 

 ment with the natural scheme above given, there would be but 

 a comparatively small deviation from the original and first pub- 

 lished colours of the map, with one partial change of name — 

 from Caradoc sandstone to May Hill sandstone. The Silurian 

 Map of the Usk, of Tortworth, of May Hill and Woolhope, of 

 Presteign, of the Malverns and Abberley, &c., would, with one 

 almost evanescent exception, remain unchanged. The Caradoc 

 and Llandeilo colours must go out from the map ; but the loss 

 will be amply compensated by a great extension of the May Hill 

 colour over many tracts that were coloured Cambrian in the 

 original Silurian Map, through the chain of the Berwyns, and in 

 a range of hills from the neighbourhood of Corwen to Conway. 

 What I stated to the Geological Society (in my paper of 

 February 25, 1852) as an hypothesis, some one might think too 

 partial to my own views, I can now state with more confidence 

 on the authority of one of the greatest of the living geologists 

 of America. His words are as follows : — " I am satisfied that 

 the evidence from fossils entirely sustains your remarks — that 



