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four upper rays curving upward, and the four lower ones 
downward. Prof: Martin gave other particulars of his visit to 
this locality, which had added nothing, however, to what had 
previously been described by Mr. Ford, whose labors have 
revealed one of the best Primordial localities in the eastern 
states, and given us several new and valuable species from 
that most interesting horizon. 
Dr. R. P. STEVENS also made some remarks on this deposit. 
The Salina Group. 
The President exhibited a series of specimens representing 
the Salina group of the Upper Silurian in the State of New 
York, and reported the results of recent observations on the 
extension of these rocks into Ohio. He said that the Salina 
group was composed mainly of red and green marls, or 
calcareous shales, with bands of sandstone and impure lime- 
stone, attaining a thickness of several hundred feet in central 
‘New York. According io his view, these sediments were 
deposited in an arm or reach of the sea bordered by the 
Canadian highlands and the Adirondacks on the north, the 
Blue Ridge on the east, and the Cincinnati axis on the west ; 
and that in this area the Niagara sea was drained away so as 
to leave an extensive basin, to which the salt water of the 
ocean had imperfect access, and where by evaporation its 
saline constituents were concentrated and finally precipitated, 
with such earthy sediments as were derived from the wash of 
the surrounding shores. 
On its western margin the Salina group had been traced to 
a “feather edge” on the flanks of the Cincinnati axis, and in 
Ohio it diminishes from a thickness of 40 or 50 feet, including 
several layers of gypsum, about Sandusky, to a thickness of 
12 feet at Tiffin, and 1 foot at Moore’s Mills. We have here 
proof that the sea-level in the Salina period was considerably 
lower than in either the preceding Niagara or the succeeding 
Helderberg epoch. Prof. Newberry also stated that so far as 
his observation had extended, the gypsum of the Salina is 
