Maryland Geological Survey 31 



De Lapparent considered the Middle Devonian of North America as 

 composed of the Corniferous (Onondaga) limestone, Marcellus shale and 

 Hamilton beds/ The IMarcellus shale he correlated with the upper part 

 of the Eifelian stage and lower part of the Givetian while the Hamilton 

 beds represent the remaining and greater part of the latter stage. He also 

 gave the lower Marcellus shale as representing the upper part of the 

 shales of OgAvell House and then the remaining portion together with 

 the Hamilton beds as synchronous with the Ilfracombe or Plymouth beds 

 of Devonshire, England.' 



Professor Kayser in the table of the Devonian formations of New 

 York in the second edition of his Formationskunde gave the Middle 

 Devonian as composed of the Marcellus shale and Hamilton beds ; ' but 

 in the text he said : The x\merican geologists generally still classify the 

 Onondaga limestone as Lower De\onian ; according to European ex- 

 perience one would rather be inclined to classify it entirely or mostly 

 as Middle Devonian. The great similarity of the characteristic Spirifer 

 aeuminahis with our S. cultrijugatus argues for this elassifieation.* 



Eegarding the classification oi the Hamilton he wrote : Although the 

 Hamilton shale locally might represent the entire Middle Devonian yet 

 on the whole it corresponds to the upper division. This is surely shown by 

 the frequent overlying beds of the Tully limestone and Genesee shale, the 

 first of which contains the Brachiopod fauna of our Iberg limestone 

 {Ehynchonella veniistula-ctihoides, etc.).' 



The third edition of this standard reference work, however, gives the 

 Middle Devonian as composed of the Schoharie grit, Onondaga limestone, 

 Marcellus shale and Hamilton beds " which differs from the classification 

 of the Middle Devonian of New York by Clarke in the exclusion of the 

 Esopus grit. 



' Traite Geol., 4th ed., 1900, p. 857. 



'Ibid., p. 869. 



^ Lehr. d. geol. Formationskunde, 1902, p. 150. 



'Ibid., p. 151. 



^ Ibid., p. 151. 



^Ibid., 1908, p. 172. 



