232 
PALAEONTOLOGY OF NEW YORK. 
ness, but of a less calcareous character, has afforded nineteen species ; while the 
Waverly, the Lower Carboniferous limestones and the Coal Measures have 
recorded seven, eight and eight species respectively. 
So far as we now perceive, the development of the Orthoceratites does not 
depend upon the duration of the deposition, or thickness of the formation. The 
Black-river limestone, of a few feet in thickness, and the Schoharie grit, of not 
more than thirty feet in thickness, have each as many species of Orthoceras re¬ 
corded as any single group, except the Hudson-river, Niagara, and the Hamilton. 
The following table shows the vertical distribution of eighteen species of the 
preceding table, which are known to occur in more than one geological formation: 
Lower Silurian. 
Middle Silurian. 
SPECIES. 
Culciferous sandstone. 
Quebeo group. 
Chazy limestone. 
Black River limestone. 
Trenton group. 
Utica slate. 
Hudson River group. 
“ Anticosti group.” 
Medina sandstone. 
Clinton group. 
Niagara group. 
Orthoceras, Breynius: 
allumettense, Billings 
* 
*• 
amplicameratiun, Hall 
* 
* 
anellum. Conrad .... 
* 
* 
anrmlatum, Sowerby 
* 
arcuoliratum. Hall .... 
* 
* 
bilir.eatum, Hall .... 
* 
* 
decrescens, Billings 
* 
* 
fei’um, Billings .... 
formosum, Billings 
* 
* 
* 
fusiforme, Hall .... 
hastatum, Billings .... 
* 
* 
* 
* 
laqueatum, Hall 
* 
* 
* 
* 
* 
Minganense, Billings 
* 
* 
. 
Murrayi, Billings 
* 
* 
Ottawaense, Billings 
* 
* 
planoconvexum, Hall . 
* 
* 
Sieboldi, Billings .... 
* 
* 
tenuifilum, Hall .... 
* 
* 
virgulatum, Hall .... 
* 
* 
