70 THE DEVONIAN AND CARBONIFEROUS. tuuLL.80. 



of Gothland, and the five inferior groups of the Helderberg division as 

 the equivalent of the Ludlow rocks. 



In M. de VerneuiPs opinion the Devonian begins with the Oriskany 

 and includes the five superior groups of the Helderberg division and 

 the six groups of the Erie division and the Old lied sandstone. His 

 argument for beginning the Devonian with the Oriskany is the paleon- 

 tologic equivalency of its fauna with the fauna of the European Devo- 

 nian, the occurrence of Asterolepis in Schoharie grit, and the characters 

 of tljjB numerous Spirifera, some of which reminded him of Spirifer cul- 

 trijugatus and S. macropterus of the Eifel, and thefact observed by Hall 

 that the Oriskany was preceded by a violent movement of the waters, 

 denuding and wearing depressions in the underlying rocks. The Oris- 

 kany he regarded as the equivalent of the fossiliferous schists of the 

 border of the Ehine. The Chemung, Portage, Genesee, Tully, and 

 Hamilton represented for him the formations of the Eifel and Devon- 

 shire ; the Marcellus shales, those of Weissenbach in Nassau ; the black 

 (Devonian) schists of Ohio, Indiana, and Kentucky, he regarded as 

 representing the Genesee slates of New York, and the calcareous band 

 below represented the Corniferous and Onondaga limestones and the 

 Hamilton group of the East. He held that the Devonian disappears 

 entirely on the borders of the Mississippi, where the Carboniferous sys- 

 tem rests directly on the Silurian. 1 



M. de Verneuil first pointed out the fact that the u Waverly series " 

 of Ohio and Indiana in great part belonged to the Carboniferous sys- 

 tem, and not to the Devonian or Chemung, as American geologists 

 held. 2 This determination was based upon study of the fossils from 

 near Medina, and from Cuyahoga, and Newark, Ohio. He showed that 

 the representative of the Portage in Ohio was possibly at the base of 

 the Waverly sandstone, but found it difficult to draw a line on account 

 of the lack of fossils, and held the view that in Indiana, Kentucky, 

 and Tennessee all above the black slates is Carboniferous. 



In a foot note 3 Mr. Hall explains that he had called rocks at New 

 Albany, Indiana, lying above the black slates and containing Carbon- 

 iferous fossils, u Subcarboniferous, from the fact that up to that time I 

 was not aware that anything below the base of the great Carboniferous 

 limestone had been recognized as belonging to the Carboniferous 

 period." 



In Tennessee the siliceous strata of Prof. Troost are also reported as 

 belonging to the Carboniferous system. Those " Psammites and sili- 

 ceous strata' 7 M. de Verneuil regarded as equivalent to the " yellow sand- 

 stone of Ireland" and the " slates and sandstones of Westphalia." 



The reviewer at the close still differed from the author in his defini- 

 tion of the Devonian system above and below, insisting that the limit 

 between Silurian and Devonian should be at the base of the Schoharie 



* Am. Jour. Sci., 2d ser., vol. 5, p. 181. 2 Ibid., vol. 7, p. 45. 8 Ibid., p. 461. 



