DEVONIAN AND MISSISSIPPIAN FAUNAS 95 



nian types of life persisted to such an extent that the Gaspe sandstone 

 has sometimes been correlated with the Oriskany of the Eastern Conti- 

 nental Province. It has been shown by Clarke, however, that asso- 

 ciated with these Lower Devonian types there is a much more impor- 

 tant element which allies the fauna with the Hamilton of the interior, 

 the evidence being sufficient fully to justify the correlation of the Gaspe 

 sandstone with the Middle Devonian. The Onondaga fauna is not 

 differentiated in the Gaspe region. 



The origin of the Hamilton fauna in the Gaspe basin is assumed by 

 Clarke to have been by migration from the interior by way of the 

 Connecticut and St. Lawrence troughs, and the presence of a similar 

 fauna, showing a mingling of Oriskany and Hamilton types, on the 

 island of St. Helen's near Montreal, gives some strength to such an 

 assumption. However, the possibility of a southern origin, by way of 

 the Atlantic border, should not be lost sight of. 



THE EASTERN CONTINENTAL PROVINCE 



Middle Devonian of the Eastern Continental Province. — In the 

 Eastern Continental Province two major divisions of the Middle 

 Devonian, the Onondaga and the Hamilton, are clearly recognized. 

 These two faunas, with only minor, subprovincial differences, are 

 persistent throughout the province, in New York, Ontario, Michigan, 

 the Ohio Valley both east and west of the Cincinnati arch, in southern 

 Illinois, and even in northeastern Mississippi and northern Alabama. 

 The Onondaga fauna is in part an evolution product from the sub- 

 jacent Oriskany, but, in addition, there are included in it at least three 

 conspicuous elements which are entirely new, the corals, the cephalo- 

 pods, and the fishes. This fauna has a greater distribution to the north 

 than the superjacent Hamilton, it alone being represented in the out- 

 lying areas at Lake Memphremagog and James Bay. East of the Cin- 

 cinnati arch, which was evidently a peninsula at this time, the Onon- 

 daga fauna does not extend far beyond the Ohio River, but west of this 

 arch it is clearly recognized as far south as northeastern Mississippi. 

 Throughout this entire area the composition of the fauna is wonder- 

 fully uniform. 



The origin of the new elements in the Onondaga fauna is not 

 entirely clear. It has been suggested by the writer' that these elements 



I Jour. Geol., X, 429. 



