J.I). Dana — SEDGWICK AND M D iu'HISON. 173 



Igwick, with all the light which the fossils of the "Silu- 

 rian System" were calculated to throw on his Upper Cambrian 

 Series, found in the work' no encroachments on his held or on 

 his views. They were still side by side in their labors among 

 the hitherto unfathomed British Paleozoic rocks. 



In 18-4-0 and L841 Murchison was in Russia with M. de 

 Yerneuil and Count Kevserling, and also in Scandinavia and 

 Bohemia, seeking to extend his knowledge of the older fossil- 

 iferous rocks and verify his conclusions ; and in 1845 the great 

 work on the Geology of Russia and the Urals came out, with a 

 further display of Upper and Lower Silurian life. In his 

 Presidential addresses of 1842 and 1813, reviewing the facts in 

 the light of his new observations, he went so far as to sav that 

 the Lower Silurian rocks were the oldest of fossiliferous rocks 

 and that the fossiliferous series of North Wales seemed to ex- 

 hibit no vestiges of auimal life different from those of the 

 Lower Silurian group. 



Srill Sedgwick made no protest. He states definitely on this 

 point in his paper of 1852," that from 1884, the time of the ex- 

 cursion with Murchison, until 1812, he had accepted Murchison's 

 conclusions, including the reference of the Meifod beds to the 

 Caradoc or Silurian, without questioning ; but that from that 

 time, 1842, he began to lose his confidence in the stability of 

 the baseline of the "Silurian System." He adds that in 1812, 

 Mr. Salter, the paleontologist, informed him that the Meifod 

 beds were on the same horizon nearly with the Bala beds ; and 

 he accepted this conclusion to its full extent, using the words 

 " if the Meifod beds were Caradoc, the Bala beds must also be 

 Caradoc or very nearly on its parallel." Thus the inference of 

 Murchison was adopted and discrepancy between them deferred. 

 And on the following page he acknowledges that all his papers 

 of which there is any notice in the Proceedings or Journal of 

 the Geological Society between 1813 and 1816 admit this view 

 as to the Bala beds and certain consequences of it — " mistakes" 

 as he pronounced them six years later, in 1852.f 



In 1843, Sedgwick read before the Geological Society in 

 June, a paper entitled An Outline of the Geological Structure 

 of North Wales, which was published in abstract in the Pro- 

 ceedings (iv, 251) ; and in November of the same year, one 

 On the Older PuJwozoic (Protozoic) Hocks of North Wales 

 (from observations by himself in company with Mr. Salter), 

 which appeared, with a map, in the Journal of the Geological 

 Society (i, 1). The abstract in the Proceedings was prepared 

 by Mr. Warburton, the President- of the Geological Society, and 

 the paper of the following November, makes no allusion to 

 this fact, or any objection to the abstract. 



* Q. J. Geol. Soc, viii, 153, 1852. f Ibid., p. 154. 



