FISHES OF THE DEVONIAN AGE. 
The Devonian system is perhaps better represented in eastern North 
America than anywhere else, and the rocks of this age form an important 
part of the splendid Paleozoic section exposed between the Adirondacks and 
the Pennsylvania line, worked out with so much care by the New York 
geologists. 
The Devonian rocks here form three great natural groups, as follows: 
Portage shales. 
| Genesee shale. Huron shale. 
Tully limestone. [ 
1. Hamilton group.... 4 Moscow shale. J 
Enerinal limestone. 
; Blue shale. 
(Marcellus shale. 
; Corniferous limestone. 
2 Onondaga limestone. 
( Schoharie grit. 
3. Oriskany group .--.< Caudagalli grit. 
Oriskany sandstone. 
2. Corniferous group.. 
By some geologists the Oriskany sandstone is made the summit of the 
Upper Silurian system, but it was included in the Devonian by the mem- 
bers of the New York survey and by Lyell and Verneuil, who personally 
examined the New York section, and it certainly forms the natural base of 
that system. The Oriskany group is a mass of mechanical sediment, which 
marks a period of physical change, and in places is plainly unconformable 
with the Upper Silurian strata. In New York the fossils of the Oriskany 
are different from those of the Silurian below and the Corniferous above, 
but at De Cewville, Canada, the most charaeteristic Oriskany fossils, such 
as Spirifer arenosus, Streptorhynchus hipparionyx, Rensselaria ovoides, ete., are 
found mingled with Corniferous species and binding the two groups together. 
The Devonian age has been called the age of fishes, because all over 
the world the rocks of this system contain the remains of fishes as their 
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