390 Frof. T. Sterry Sunt — On Cambrian and Silurian. 



in certain prominent localities were publislied Lower Silurian 

 species. Meanwhile, by adopting the word Cambrian, my friend and 

 myself were certain that whatever might prove to be its zoological 

 distinctions, this great system of slaty rocks being evidently inferior 

 to those zones which had been worked out as Silurian types, no 



ambiguity could hereafter arise In regard, however, to a 



descending zoological order, it still remained to be proved whether 

 there was any type of fossils in the mass of the Cambrian rocks 

 different from those of the Lower Silurian series. If the appeal to 

 nature should be answered in the negative, then it was clear that the 

 Lower Silurian type must be considered the true base of what I had 

 named the Protozoic rocks; but if characteristic new forms were 

 discovered, then would the Cambrian rocks, whose place was so well 

 established in the descending series, have also their own fauna, and 

 the PalfBozoic base would necessarily be removed to a lower horizon." 

 If the first of these alternatives should be established, or, in other 

 words, if the fauna of the Cambrian rocks was found to be identical 

 with that of the Lower Silurian, then, in the author's language, 

 " the term Cambrian must cease to be used in zoological classifica- 

 tion, it being, in that sense, synonymous with Lower Silurian." 

 That such was the result of Palseontological inquiry, Murchison pro- 

 ceeded to show by repeating the announcements already made by 

 Sedgwick in 1837 and 1838, that the collections made by the latter 

 from the great series of fossiliferous strata in the Berwyns, from 

 Bala, from Snowdon and other Cambrian tracts, were identical with 

 the Lower Silurian forms. These strata, it was said, contain 

 throughout "the same forms of OrfAis which typify the Lower Silurian 

 rocks." It was farther declared by Murchison in this address, that 

 researches in Germany, Belgium, and Eussia led to the conclusion 

 that the "fossiliferous strata characterized by Lower Silurian OrtMd(& 

 are the oldest beds in which organic life has been detected." (Proc. 

 Geol. Soc, vol. iii. p. 641, et seq.) The Orthids here referred to are, 

 according to Salter, Orthis calligramma, Dalm, and its varieties. 

 (Mem. Geol. Survey, vol. iii. part 2, pp. 335—337.) 



Meanwhile Sedgwick's views and position began to be misrepre- 

 sented. In 1842 Mr. Sharpe, after calling attention to the fact that 

 the fossils of the Bala limestone were, as Sedgwick had long before 

 shown, identical with those of Murchison's Lower Silurian, declared 

 that Sedgwick had placed the Upper Cambrian, in which the Bala 

 beds v/ere included, beneath the Silurian, and that this determination 

 had been adopted by Murchison on Sedgwick's authority. (Proc. 

 Geol. Soc. vol. iv.p. 10.) This statement Murchison suffered to pass un- 

 corrected in a complimentary review of Sharpe's paper in his next 

 annual address (1843). In his Siluria, 1st edition, page 25 (1854), 

 he speaks of the term Cambrian as applied (in 1835) by Sedgwick 

 and himself ^' to a vast succession of fossiliferous strata containing 

 undescribed fossils, the whole of which were supposed to rise up 

 from beneath well-known Silurian rocks. The Government geolo- 

 gists have shown that this supposed oi'der of superj)osition was 

 erroneous," etc. The italics are the author's. Such language, 

 coupled with Mr. Sharpe's assertion noticed above, helped to fix 



