692 PROCEEDINGS OF THE BALTIMORE MEETING 



not as easy to account for the forerunners of the Hamilton species in the 

 Oriskanian of America as in the Lower Coblenzian of Europe? 



There is, moreover, positive difficulty in accounting for the combination of 

 species in the Hamiltonian epoch of North America. In order to account for 

 the mixing of Hamilton species with Oriskanian -it is necessary to imagine the 

 Oriskanian species living through the Onondagaian epoch. Evidence of the 

 Onondagaian fauna is known in the Chaudiere River beds, but containing no 

 trace of the dominant Oriskanian species supposed to have lived over except 

 Leptocoelia fla~bellites, which is also known in the Onondaga formation of the 

 interior, and no Hamiltonian fauna in the country has any mixture of Oris- 

 kanian species. The Chaudiere beds are midway between the Gaspe and Saint 

 Helens beds. How will we account for the continuance of the Oriskany species 

 till Hamiltonian epoch without showing some trace of themselves in the inter- 

 val or in the typical basin of Hamilton sediments, with which open connection 

 with the Gaspe locality has been assumed? 



Not only are the underlying Grande Greve limestones filled with a domi- 

 nantly Oriskanian fauna, but the Nictaux beds, Nova Scotia, the Campbell 

 River beds in New Brunswick, the Chapman sandstone in Aroostook county, 

 the Moose River sandstone in Somerset county, Maine, and the Upper Saint 

 Helens and Cote Saint Paul, near Montreal (thus quite surrounding the Gaspe 

 peninsula), are all filled with a very closely allied fauna to that described 

 from the York River beds at the base of the Gaspe sandstone. This gives 

 strong ground for belief that there were open connected seas in which the 

 fauna lived. But inside the Connecticut- Saint Lawrence trough not the least 

 trace of the Onondagaian fauna is in evidence, and no hiatus or unconformity 

 in the Gaspe section furnishes reason for supposing that the Gaspe series 

 from the limestones upward through the sandstones was not a continuous 

 deposition. 



The combination of species in the York River beds at Gaspe, as well as in 

 the Upper Saint Helens beds and at Cote Saint Paul, near Montreal, is re- 

 markable in containing elements of two faunas mixed which we are accus- 

 tomed to find dissociated. The dissociation of the separate faunas is, however, 

 not due to the entirely different time of existence of the two faunas, but to the 

 fact that the two faunas for long periods of geologic time have occupied sepa- 

 rate areas of space on the globe. We can not maintain the idea that during 

 the Oriskanian epoch the genera, and . certainly very closely allied species of 

 the genera, which were characteristic of the Hamiltonian fauna did not 

 actually live somewhere and in a flourishing condition and in abundance during 

 the Oriskanian epoch. But they lived in a different sea basin from that in 

 which the characteristic Oriskanian fauna flourished. It is the running to- 

 gether of elements of the two faunas that is anomalous. It is possible to 

 imagine that the dominant species of the Oriskany suddenly became extinct, 

 but not that the dominant species of the Hamilton suddenly came into exist- 

 ence Without ancestors. 



It is with this point of view that in such a mixed fauna we are forced to 

 use the dominant species in determining the age of the fauna, and to regard 

 the rare and occasional species as indication of the race whose time relations 

 may date back to early Paleozoic time, if not earlier, and forward even to the 

 present time. 



