242 ROYAL SOCIETY OF CANADA 



and coarse 'sediments in Xew York sepajrating the Oriskany from the 

 Onondaga. In this interval of time it is supposed that the Nictaux, the 

 York river (Gaspé sandstone), the Moose river sandstone and 

 the upper St. Helen's beds were deposited. In these local fauna's 

 are seen traces of the second, (or Hamiltonian magnafauna), wliich did 

 not fully express its characteristics till the IsTew York Hamilton, but the 

 dominant part of the species of Lot 1 of St. Helen's belong to the second 

 pha'se of the first (or Helderberg-Oriskanian) magnafauna. 



After the barrier to the east and northeast had been established the 

 hypothesis is that a channel was opened connected with the interior 

 thj-ough the Indiana-Kentucky area and opening southward, through 

 which the Onondaga fauna migrated as far northeast as the valley of the 

 St. Lawrence. (Chaudière and Lake Memphremagog beds). 



A's to the second fauna of St. Helen's its composition indicates the 

 first phase of the Helderberg-Oriskany magnafauna, before the character- 

 istic Oriskanian species had been evolved, and it is equivalent, both 

 f aunally and temporally, to some part of the Helderbergian of the New 

 York series. 



The species of the first St. Helen's fauna, showing affinities with the 

 Hamilton magnafauna, (and the same interpretation applies to the 

 Moose river (Maine) and York river (Gaspé) beds, are accounted for by 

 the coming together of the two magnafaunas of the southern and north- 

 em Atlantic on the American border at the time of the departure of the 

 Oriskanian element rather than at the opening of the Hamilton epoch. 

 This interpretation is in harmony with the mingling of these 'same two 

 magnafaunas in the lower Devonian (Coblenzian) of Europe. 



