4 i 8 CHARLES S. PROSSER 



bones of fishes, which occurs at the top of the Columbus and separates 

 it from the Delaware limestone. x 



In discussing the correlation used by Professor Winchell in his 

 report on Delaware County, Dr. Orton said: 



The Columbus and Delaware limestones probably cover the age in which the 

 Corniferous limestone, and the Hamilton group, in part, of New York were form- 

 ing; but there seems no warrant whatever for identifying the subdivisions of our 

 scale with the subdivisions recognized five hundred or a thousand miles away. 2 



In 1877 Professor Hall visited the Falls of the Ohio, near Louis- 

 ville, and correlated the hydraulic and encrinal limestones, which 

 are the higher limestones of the section, with the Hamilton group 

 of New York, and said that "in the state of Ohio similar conditions 

 may be inferred, from the fact that certain species of known Hamilton 

 fossils are published in the Ohio Geological Reports as from the 

 Corniferous group." 3 



In 1878 Professor Whitfield visited Franklin County, and on the 

 banks of the Scioto River, six miles northwest of Columbus, made 

 the most important discovery relating to the classification of the 

 Devonian limestones that had been made in central Ohio. In a 

 bed of dark-brown, bituminous shale, in the lower part of the Dela- 

 ware limestone, flattened specimens of Liorhynchus limitaris (Van.), 

 Discina minuta Hall, and Lingula manni Hall were found, the two 

 former being strictly characteristic species of the Marcellus shale 

 of New York. On the following day the same shale was found 

 farther north, nearly opposite Dublin, containing Liorhynchus 

 limitaris (Van.) and Discina lodensis (Van.). This shale was 

 reported only a few feet above the "bone-bed," and Professor Whit- 

 field stated: "I have no hesitation in pronouncing [it] the equivalent 

 of the Marcellus shale of New York." 4 This discovery seemed 

 to confirm Professor W T inchell's opinion that the Delaware limestone 

 of Delaware County represented the Hamilton formation of New 

 York. 



1 See Ibid., pp. 605, 606, 610. 2 Ibid., p. 634. 



3 Transactions 0} the Albany Institute, Vol. IX (1879), p. 179. The same state- 

 ment was published in Palceontology of New York, Vol. V, Part II, text (1879), pp. 

 146, 147. 



4 Proceedings of the American Association for the Advancement of Science, Vol- 

 XXVIII (1880), pp. 297, 298. 



