DEVONIAN AND MISSISSIPPIAN FAUNAS 97 



During the Hamilton period the sea retreated from the northern 

 embayments in the James Bay region and the Connecticut trough, and 

 at the same time it transgressed toward the south and occupied terri- 

 tory Avhich had been dry land during Onondaga time, and connection 

 was apparently established between the eastern and western sub- 

 provinces to the south of the Cincinnati arch, which at this time 

 became an island. 



Upper Devonian of the Eastern Continental Province. — During 

 Upper Devonian time the faunas of the Eastern Continental Province 

 were far more local in their development than they had been at any 

 time during the Middle Devonian. At no time during the period was 

 there so uniform a fauna as either the Onondaga or the Hamilton had 

 been, distributed throughout the entire province. In the early Upper 

 Devonian time the sea retreated northward from its greatest south- 

 ward extension of Hamilton time, and later again transgressed toward 

 the south and southwest until it extended much farther than it had in 

 the earlier period, this retreat and readvance being recorded in the 

 unconformity at the base of the Upper Devonian black shale which is 

 commonly exhibited south of the Ohio River and to some extent north 

 of that stream.' 



The earliest Upper Devonian fauna in the province is the Cuboides 

 fauna of the Tully limestone in New York, characterized by a totally 

 new immigrant element in the Devonian faunas of the province, of which 

 the brachiopod species Hypothyris cuboides is the most conspicuous 

 representative. This fauna has been shown by Williams^ to be closely 

 allied to the Cuboides fauna of the European Devonian which initiates 

 the Upper Devonian of that continent. The Cuboides fauna in Amer- 

 ica must have had a common origin with the same fauna in Europe, 

 and the path of its immigration into the Eastern Continental Province 

 of North America is commonly considered to have been by way of the 

 Interior Continental Province. 



Following the Tully limestone in the northeastern portion of the 

 province is the Genesee black shale with a meager fauna of which the 

 Lingulas are the most conspicuous members. In the southern portion 



1 Data concerning this unconformity have been assembled by Foerste, Ky. Geol. 

 Surv., Bull. No. 7, p. 129. 



2 Bull. G. S. A., I, 481-500. 



