Maryland Geological Suuvhy 37 



Vernenil visited this country, studied the Paleozoic formations and 

 published an article correlating the Paleozoic deposits of jSTorth America 

 with those of Europe/ He included the Old Bed Sandstone or Catskill 

 group in the Devonian and after some hesitation drew the lower limit 

 at the base of the Oriskany sandstone,' and this was generally accepted 

 and followed by American geologists. In 1889, Dr. J. M. Clarke in his 

 paper on " The Hercynian question," showed that the Lower Helderberg 

 probably belongs in the Devonian instead of the Upper Silurian,' and 

 recently he and Schuchert have clearly drawn the line of division 

 between the Devonian and Silurian systems at the base of the Lower 

 Pentameras (Coeymans limestone) and transferred the Lower Helderberg 

 to the Paleodevonian.* This correlation is opposed by Prof. H. S. 

 Williams who claims that the Chapman sandstone fauna of Aroostook 

 County in northern Maine is the representative of the Tilestone fauna 

 at the top of the Silurian system in Wales, while below the Chapman 

 sandstone is the Lower Helderberg fauna.' This argument has been 

 answered by Dr. J. M. Clarke who states that these arenaceous deposits 

 of Aroostook County, 3Laine, contain Xew York Oriskany species together 

 with " A number of species identical with those of Lower Devonian 

 faunas of western Europe." " 



'Bull. Soc. Geol. France, 2d Ser., t. IV, 1847, pp. 64G-710, which was trans- 

 lated and condensed by Prof. James Hall and published in four installments 

 in the Amer. Jour. Sci. & Arts, 2d Ser., "Vols. 5 and 7. For the first part see 

 Vol. 5, 1848, p. 176. 



'Loc. cit.. p. 677. Am. Jour. Sci.. 2d Ser., Vol. .5, p. 367. 



M2d An. Rep. State Mus. [N. Y.] Nat. Hist, for 1888, p. 40S, and see espe- 

 cially pp. 422-424, 437. 



* Clarke and Schuchert, Science, N. S., Vol. X, Dec. 1.5, 1899, p. 876; Schuch- 

 ert's paper entitled " Lower Devonic aspect of the Lower Helderberg and 

 Oriskany formations," Bull. Geol. Soc. Am., Vol. 11, May, 1900, p. 241; 

 Clarke: Mem. N. Y. State Mus., No. 3, 1900 (N. Y. State Mus., 53d An. Rep. 

 Regents 1899, Vol. 2, 1901), pp. 82-101 and Handbook 19, N. Y. State Museum. 

 1903, pp. 8, 14; N. Y. State Mus. Mem. 9, 1908, p. 7; Kayser, Lehrbuch, Forma- 

 tionskunde, 3d ed.. 1908, p. 172. 



"Am. Jour. Sci., IV Ser., Vol. IV, March, 1900, p. 213; Bull. Geol, Soc. 

 Amer., Vol. 11, May, 1900, p. 346; Bull. U. S. G. S., No. 165, p. 87. 



' Science, N. S., Vol. XII, Dec. 28, 1900, p. 992; Proc. Am. Assoc. Adv. Science, 

 Vol. 49, 1900, p. 188; N. Y. State Mus., Mem. 9, Pt. 2. 



