TULLY LIMESTONE AND CUBOIDES SCHICHTEN CONTEMPORANEOUS. 499 



speaking, the point in the European time scale represented by the beginning 

 of deposition of the Cuboides Schichten of Aix la Chapelle and Budesheim is 

 represented in the New York sections by the Tully limestone ; and, second, 

 that the representative of the fauna of the Cuboides zone of Europe is seen 

 in New York not only in the Tully limestone but in the shaly strata for 

 several hundred feet above, including the High Point zone in Ontario county 

 and the Ithaca group in several counties further east. 



Therefore, if we wish to express precise correlation in our classification 

 of American rocks, the line between middle and upper Devonian formations 

 should be drawn at the base of the Tully limestone, to correspond with the 

 usage of French, Belgian, German, aud Russian geologists, who include the 

 Frasnien, Cuboides Schichten, and correlated zones in the upper Devonian. 



DISCUSSION. 



Mr. C. D. Walcott : Professor Williams' paper is of unusual interest, as 

 he has shown very clearly that the theory of Huxley that there is no homo- 

 taxial relation between the subdivision of the geologic systems on the Amer- 

 ican and European continents is not altogether correct. This study of the 

 Cuboides zone has shown one limited horizon, at least, that is widely dis- 

 tributed in Europe which is also readily recognized in the state of New York. 



