154 PROCEEDINGS OF THE GEOLOGICAL society. ([Dec. 1, 
11. Marcellus Shale. 
Moscow Shales. 
Hamilton Group. 1 Bra Limestone. 
Ludlowvilie Shales. 
Tully Limestone. 
Genesee Slate. 
In a paleontological classification these beds must be arranged 
together, so many species do they possess in common. There is also 
a mineralogical accordance in their prevailing argillaceous and shaly 
character. 
We have here some species which were found in the beds below; 
but with these we find a great variety of new species, belonging mostly 
to different genera from those common below. In this group of beds 
the Brachiopoda are less numerous, and the species of Lamellibran- 
chiata far more abundant than we have yet seen them. Among the 
latter are many species either belonging or allied to the genera Cy- 
pricardia, Cuculleea?, Avicula, Inoceramus? &c., which have a general 
resemblance to shells found in our Ludlow beds; but so few of the 
species are identical, that we cannot group these beds with the Lud- 
low formation. The shells which can be specifically identified are, 
with few exceptions, known here in the Devonian or carboniferous 
formations, so that we must undoubtedly refer the beds of this group 
to the Devonian period. 
The Hamilton group is perhaps the richest in species of all the 
New York beds, and its specimens are usually well preserved ; still 
I am not able to identify a large proportion of its species with those 
of Europe. The following occur in Mr. Lyell’s collection :— 
Avicula Boydii. Spirifer Urii. 
guadrula. macronotus. 
Athyris concentrica. Productus fragaria ? 
lamellosa. scabriculus ? 
Orthis Michelini. Terebratula reticularis. 
eximia ? aspera. 
opercularis. borealis. 
nucula ? 
Orthoceras articulatum? 
Strophomena Sharpei. 
12. Portage Group. 
This is described by Mr. Hall as an extensive development of 
shales, flagstones and sandstones, at least 1000 feet thick, with very 
few organic remains; of these Mr. Lyell’s collection contaims no spe- 
cimens: the few species described by Mr. Hall connect the Portage 
group with the beds both above and below it: the principal cha- 
racter being the negative one, that it is almost bare of fossils, though 
lymg between two beds richly supplied with them: in all these re- 
spects it resembles part of our Devonian series. 
13. Chemung Group. 
This group consists, according to Mr. Hall, of ‘a highly fossili- 
ferous series of shales and thin-bedded sandstones,”’ scarcely less, in 
the eastern part of his district, than 1500 feet thick. Many of the 
ee ee oe a 
’ 
, 
* 
: 
¥ 
