6 



PALEONTOLOGY OF THE EUBEKA DISTRICT. 



considered Cardiomorpha Missouriensis and fragments of a Spirifera of the 

 type of Spirifera Rockymontana Marcou ( KeokuJc Hall), as probably 

 indicating a division of the black shales into Carboniferous and Devonian, 

 but, from field observations and the assemblage of fossils, such a division 

 is incompatible with the facts. The White Pine shales occupy the same 

 position with relation to the Devonian and the Carboniferous systems as 

 does the lower portion of the Pogonip limestone to the Cambrian and Silu- 

 rian systems. In each case there are beds of passage carrying a fauna that 

 unite the faunas of the two systems. 



That the Devonian portion of the White Pine shale fauna is more 

 nearly related to that of the shales of the Hamilton Group than that of the 

 Chemung horizon, as found in the neighboring Eureka District, is owing 

 undoubtedly to the character of' the environment of the fauna during the 

 deposition of the shales, a feature so well shown in the recurrent faunas of 

 the Devonian of New York as studied by Prof. H. S. Williams. 



A summary of the Devonian fauna is given in the following table: 



* And five varieties. 



Of the two hundred and twenty-five species, sixty-one are described 

 for the first time, forty-five species are referred to genera but not specifi- 



