THE DEVONIAN SECTION OF ITHACA, N. Y. 595 



by me in 1884/ and it was then shown to range "through approxi- 

 mately 1300" feet, including the "Ithaca group." It was then 

 spoken of as the Cardiola speciosa fauna. In 1886^ this general 

 fauna was differentiated into the several stages, Lingula fauna, 

 characteristic of the black shales; Cephalopod fauna, found more 

 frequently in the green shales; and the special Cardiola speciosa 

 fauna also occurring in the greenish shales, but often disassociated 

 from the Cephalopods. In 1887^ these faunal distinctions were 

 more fully elaborated and defined for the Genesee section. In 

 18854 J. M. Clarke described the fauna and flora of the Naples beds 

 of Ontario county, there proposing the term "Naples beds" to include 

 the Cashaqua and Gardeau members of the Portage or Nunda 

 group of Hall; and in 1898 and 1904^ the fauna was more fully 

 elaborated by him under the name of the "Naples fauna," and its 

 intimate relations to the European Intumescens fauna was also 

 indicated. 



ALTERNATION OF DISTINCT FAUNA 



In the paper of 1887'' the Nunda fauna was shown to run up in 

 the strata at Hornellsville high enough to be mingled with species 

 of the distinctive Chemung fauna. ^ This fact of the alternation 

 of the representatives of two distinct faunas in the zone of tran- 

 sition from one fauna to another has been repeatedly observed in 

 later studies. It led me to the necessity of assuming that two faunas 

 normally appearing one above the other in direct succession owe 

 their order of succession to shifting of their local habitat in the same 

 oceanic basin (i. e., marine faunas), rather than to any absolute 



1 Bulletin No. j, U. S. Geological Survey (1884). 



2 "On the Classification of the Upper Devonian," Proceedings of the American 

 Association for the Advancement of Science, Vol. XXXIV (1886). 



3 Henry S. Williams, "On the Fossil Faunas of the Upper Devonian-the Gene- 

 see Section, New York," Bulletin No. 41, U. S. Geological Survey (1887). 



4 John M. Clarke, "On the Higher Devonian Faunas of Ontario County, Nevi^ 

 York," Bulletin No. 16, U. S. Geological Survey (1885). 



s Memoir No. 6, New York State Museum, "Naples Fauna in Western New 

 York," Parts i and 2 (1898 and 1904). 



6 Bulletin No. 41, U. S. Geological Survey. 



7 Ibid., p. 80. 



