Wi33che]l.] '*'J" [May 6, 



of western formations in 1841, lie states:'^^ " This examination westward 

 also afforded a good opportunity of testing the value of fossil characters, 

 when applied to the same strata extending over wide tracts of country, 

 and tlie results will be seen, as we proceed, to have been mostly satisfac- 

 tory." On another occasion he used the following words:'^? "Every step 

 in this research tends to convince us that the succession of strata, when 

 clearly shown, furnishes conclusive proofs of the existence of a regular 

 sequence among the earlier organisms;" Finally, in 1850, he employed 

 this explicit and pertinent language :'38 " In distant and disconnected lo- 

 calities we are compelled to base our opinions of the equivalency of beds 

 upon the organic remains which they contain." 



Such citations could be made almost without limit, but it scarcely seems 

 necessary to proceed. Every paleontological research proceeds upon the 

 assumption of the truths of the fundamental principles which these ex- 

 tracts enunciate. On paleontological grounds Professor Hall undertook 

 the identification of the western formations; on such gronnds he asserted 

 the Spergen Hill limestone to belong to the age of the Warsaw limestone; 

 on such grounds Mr. Billings identified the Lower Helderberg group in 

 Maine; on such grounds Barrande divides his Promodial Zone into dis- 

 tinct stages which he attempts to identify in other parts of the world; 

 on such grounds Barrande confidently asserted, without even having 

 placed foot upon American soil, that certain Trilobites described by Profes- 

 sor Hall from the town of Georgia, in Yermont, belonged to a much low- 

 er, stratigraphical position than had been assigned to them; and thus, 

 while sitting in his study at Paris, confidently and successfully rectified the 

 mistakes of field geologists in America working amongst the hills of 

 northern New England. 



It is evident that if we proceed according to the established principles 

 of paleontological science, we shall be obliged to deny the contempora- 

 neous origin of the rocks of the Marshall and Chemung groups. We shall 

 be indu^ced to leave the Chemung within the limits of the Devonian sys- 

 tem where it has teen placed by the nearly unanimous judgment of pale- 

 onto'.ogists; and to admit the Marshall group within the boundaries of 

 the Carboniferous system according to the present nearly unanimous judg- 

 ment of western geologists;'^^ according to the opinions of the eminent 

 European geologists who have investigated the question, and according 

 also to views which were at one time shadowed forth by the present prin- 

 cipal opponent of such views. De Verneuil'*" in alluding to certain rep- 

 resentatives of the Marshall group, says: "As it [the Devonian system in 

 New York] is principally composed of Schists and argillaceous sandstones 

 which, as we liave said, are lost and disappear in the West, it thence re- 

 sults that in the States of Ohio, Indiana and Kentucky, it is reduced to 



138 Trans. Asssoc. Amer. Geol. p. 26«. 



137 Paleont. N. Y., vol. I. Introd. p. xxxiii. 



1=8 Foster and Whitney's Eep. Lake Sup. Land Dis. IX. p. 286. 



139 See the references made in the 2d section of this paper. 

 ii» See Amer. Jour. Soc. [2] v. 3"0. 



