REPORT OF THE STATE FALEONTOLOGIST 1901 671 



ground. It is indigene, for its ancestry had taken and lost pos- 

 sessions early in Mareellus time by invasions from the west, re- 

 taken and held possession from the beginning of Hamilton 

 time. It is to be noted that through a part of the extent of the 

 Ithaca sediments there is nothing separating them from the 

 Hamilton beds below, the Tully limestone and Genesee shale 

 feathering west of the Chenango valley. 



Oneonta fauna 



Contemporaneous with the latter part of Ithaca sedi- 

 mentation was the sparse fauna of the Oneonta sandstones. 

 These we believe to have been deposited in a narrow coastal 

 lagoon, and its few characteristic organisms, Amnigenia 

 catskillensis, Estheria membranacea, are of 

 fresh-water habit. The latter occurs in the Old Red lakes 

 of northern Scotland, species of the former in nonmarine de- 

 posits of Ireland and the Eifel. We are left to surmise that 

 these species found their way into New York by fresh or 

 brackish water passage from the Old Red lakes of Nova Scotia 

 (Arisaig) and Quebec (Gasped). 



The CatsMU. The Catskill represents a continuation of One- 

 onta sedimentation; that is, deposition in a deep embayment but 

 with freer access to the open waters of the gulf, thus constitut- 

 ing a long and narrow estuary extending far southward parallel 

 to Appalachian trend. It may well be compared to the condi- 

 tions now existing in the Lake of Stennis in the Orkney main- 

 land as described by Hugh Miller, in which the upper reaches 

 are fresh and bear a fresh or depauperated brackish water 

 fauna while the lower parts are salt and marine. We know 

 that this condition (including the deposits of the Oneonta) pre- 

 vailed in eastern New York from the close of the Hamilton 

 through Portage and Chemung time and in southern New York 

 continued into the early Carbonic. 



Chemung fauna 

 The main body of the Chemung fauna is the direct derivative 

 along the long line of descent from the Hamilton through the 



