524 NEW YORK STATE MUSEUM 



2 Those which are restricted to the Newfoundland embayment 

 and Champlain basins : Tarphyceras, Deltoceras and Plectoceras. 



3 Those which have their principal development in the Newfound- 

 land embayment and Champlain basin (or Appalachian trough), and 

 are not known in Europe, but extended also to the Pacific-American 

 basin : Eurystomites. A more complete knowledge of the cephalo- 

 pod faunas of the earliest Lower Siluric of the west would prob- 

 ably bring some or all of the genera cited under 2 into this group. 



4 Those which are better represented in Europe than in the Cham- 

 plain or Newfoundland basins : the family Lituitidae, and Schroed- 

 eroceras, Trocholites and Barrandeoceras. 



Besides these the small genus Litoceras is thus far restricted to 

 the Newfoundland basin and Piloceras which centers in the New- 

 foundland and Canadian basins has reached the Mississippian basin 

 on one side and England on the other. 



The existence of these groups of genera leads to the recognition 

 of the following components of the cephalopod faunas of the Cham- 

 plain basin in early Lower Siluric time : 



1 A Pacific-American element, foreign to the European seas, and 

 in part also to the Newfoundland embayment. 



2 A Newfoundland-Champlain element which may be a part of 

 the former group. 



3 An Atlantic-Bohemian element, extending into the Newfound- 

 land embayment. 



4 A Baltic element which in very small parts has reached the 

 Newfoundland embayment and Champlain basin. 



An attempt to weigh off accurately the relative importance of 

 these elements in the composition of the Champlain faunas would, 

 with our insufficient knowledge of the western faunas and the omis- 

 sion of the orthoceraconic and cyrtoceraconic forms, be premature 

 and wholly unwarranted by the data at hand. Still so much is sug- 

 gested by the foregoing analysis that the Pacific-American element 

 in the Champlain basin fauna may turn out to be greatly more im- 

 portant than the European one. This is indicated by the distribution 

 01 the genera Eurystomites, Gonioceras and Trocholitoceras, dis- 

 cussed before, and quite strongly supported by the presence of 

 Eurystomites kel 1 oggi in both the Appalachian trough 

 (including Champlain basin) and the American epicontinental or 

 Mississippian sea. It is further suggested by the fact that the At- 

 lantic-Bohemian element is practically absent in the Champlain basin 

 and apparently not so strongly represented in the Newfoundland 

 embayment as one should expect. 



