364 Parallelism of the Paleozoic Deposits 
Silurian System, (superior stage.)—We comprise under this 
title, with the sandstones which terminate the Champlain divis- 
ion, three groups which the geologists of New York unite under 
part is of little importance, being limited to the territory of New 
York,* while the Clinton and Niagara groups which compose the 
Ontario division, occupy an immense extent in the western regions 
of the United States. If we compare these groups with those 
which constitute the upper Silurian stage in Europe, we caunot 
for an instant doubt, that the limestones and shales of the Niag- 
ara group are the exact equivalents of the limestones and slates 
of Wenlock and of Gothland; so great is the number of identi- 
cal species. Hence it follows that the Clinton group, with the 
entamerus oblongus, represents the extreme upper part of the 
Caradoc sandstone, or a stage intermediate between the Wenlock 
and Caradoc beds; while the five inferior groups of the Helder- 
berg division represent the rocks of Ludlow. The Pentamerus 
oblongus, this fossil so widely distributed in America and in Eu- 
rope, occupies always the same horizon, and is everywhere found 
at the junction of the two divisions of the Silurian system ; eX- 
cept that in England it is placed in the inferior stage, while in 
America it forms rather a part of the superior stage. 
The identical species between Europe and America are here 
more numerous than in the preceding stage. We have recog- 
nized the following species: Calymene Blumenbachii, C. punc- 
tata, Phacops Hausmanni, U. limulurus, Bumastis Barriensis, 
‘Hloniaintstus delphinocephalus, Cheirures insignis, Spharexo- 
chus mirus, Agnostus latus, Orthoceratites annulatus, Bellero- 
sa dilatatus, Terebratula cuneata, T. ag T.. reticularis, 
aspera, T’. hemispherica, T. tumida, T'. Wilsoni, Pentame 
rus oblongus, Fe” + anges Spirifer cyrtena, S. trapez zoidalis, 
e presume M. de Verneuil alludes to the western extension of the Oriskany 
sands for 1t has been shown by Prof. Rogers to be of great thickness and im 
portance in Pennsylvania.—J. H. 
fie estern States the Pentamerus obl. ongus i to have pro olonged 
its existence into the Niagara group; at least, m is often very difficult to poe 
en from this group the limestones which contain it.” ve sho n the 
port on the Geology of New York and Saeae ere, that in its western extension 
t 
nglon 
sees or 
mencement of the second n the s’ a niche. 
the first volume of the psd of > Youk nd ra 
