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PALEONTOLOGY OF NEW-YORK. 
CHONETES OF THE CHEMUNG GROUP. 
In certain localities of the Chemung group, within the State of New- 
York, there are numerous specimens of Chonetes; but they occur in the 
condition of casts of the interior, or of impressions of the exterior of the 
shell. The strata containing them present all the phases of argillaceous and 
arenaceous admixtures, sometimes a soft evenly laminated shale, and 
sometimes a coarse ferruginous sandstone. The fossils therefore present 
a great variety of aspect, and very different degrees of perfection and of 
prominence in the characteristic markings. 
This condition, moreover, renders it the more difficult to make satis¬ 
factory comparisons with specimens retaining the shell, and occurring 
in other kinds of sediment. Notwithstanding these difficulties, I have, 
after much labor, satisfied myself that the greater part of all the speci¬ 
mens found in the Chemung group may be referred to three of the forms 
described from the Hamilton group : these are C. scitula , C. lepida and 
C. setigera. The two former, which I have sometimes been disposed to 
regard as perhaps identical species, maintain in the Chemung group the 
same differences that they show in the Hamilton group. There are a few 
obscure remains which do not appear referable to the preceding, having 
more numerous striae than C. scitula and approaching in character C. 
Illinois ensis. 
In the higher strata of the Chemung group in Chautauqua county, and 
in similar beds at Meadville, Pa., a very marked and distinct species of 
Chonetes has been found. In its larger examples it equals in size and 
has the general form of C. coronata of the Hamilton group, but is readily 
distinguished by having a truncate apex and the surface studded with 
slender spines. 
In extending our.researches beyond the limits of the State of New- 
York, we find in the shales and sandstones of Eastern Ohio (which in 
part I regard as representing the Chemung group), one or two species 
not known in New-York : these, however, are associated with the Cho- 
