J. 1). Dana — SEDGWICK AND MURCHISON. 177 



Society in February of that year — making the latter part of a 

 memoir by him on the "Classification and Nomenclature of 



the Lower PalflBOZOlC Rocks of England and Wales" — argues, 

 like that of 1 S -M'». for the extension of the Cambrian from 

 below upward to include the Bala beds, and thereby also 

 the Llandeilo flags, and Caradoc Band s tone, although, he says 



*• my friend lias published a magnificent series of fossils from the 

 Llandeilo flagstone.' 3 Sedgwick also expresses dissatisfaction 

 with Mr. Warburton's abstract of his paper of dune, 1843, and 

 with the change made in his map of November, 1843, as indi- 

 cated on page 174, but, as there shown, lie has no blame for 

 Murchison and little for Mr. Warburton. lie also points out 

 Minu' errors in the stratigraphical sections of the "Silurian 

 System," — since the publication of which fourteen years had 

 passed. He closes with the words (p. 16S) : 



"I affirm that the name 'Silurian,' given to the great Cambrian 

 series below the Caradoc Group, is historically unjust. I claim 

 this great scries as my own by the undoubted right of conquest; 

 and I continue to give it the name ' Cambrian' on the right of 

 priority, and, moreover, as the only name yet given to the series 

 that does not involve a geographical contradiction. The name 

 'Silurian' not merely involves a principle of nomenclature that is 

 at war with the rational logic through which every other Palaeo- 

 zoic group of England has gained a permanent name, but it also 

 confers the presumed honor of a conquest over the older rocks of 

 Wales on the part of one who barely touched their outskirts and 

 mistook his way as soon as he had passed within them. 



" I claim the right of naming the Cambrian rocks beeause I 

 flinched not from their difficulties, made out their general struc- 

 ture, collected their fossils, and first comprehended their respec- 

 tive relations to the groups above them and below them, in the 

 great and complicated Palaeozoic sections of North Wales. Nor 

 is this all, — I claim the name Cambrian in the sense in which I 

 have used it, as a means of establishing a congruous nomencla- 

 ture between the Welsh and the Cumbrian Mountains, and bring- 

 ing their respective groups into a rigid geological comparison; 

 for the system on which 1 have for many years been laboring is 

 not partial and one-sided, but general and for all England." 



Sedgwick does not seem to have recognized the fact that 

 Murchison had the same right to extend the Silurian system to 

 the base of the Llandeilo beds, whatever its horizon, that he 

 had to continue the Cambrian to the top of the Bala bed- 



* One important fact is pointed out in this paper in a letter from M'Coy, on 

 page 143: that the May Hill group, which Murchison had referred to the Caradoc 

 series, really belonged by its fossils to the Upper Silurian. This point was the 

 subject of a paper by Sedgwick in the next volume (vol. ix) of the Journal of the 

 Geological Society. 



