346 J.B. Perry on the Geology of Vermont. 
tions which, in some localities, are from 25,000 to 30,000 feet 
in thickness, 
Thus, we have brought before us certain facts and relations 
pertaining to the Primordial formations, which each person 
may observe for himself. In the light of these facts and rela- 
tions, we are enabled to see the utter untenableness of the 
position that these beds are Lower Silurian, in the proper 
sense of that designation. According to the view suggested 
y the considerations presented, it may seem strange that any 
mistake should have been made in regard to these rocks. If, 
however, we look at the matter in another light, and remem- 
ber that our geologists regarded the Red Sandstone as of 
edin , we can discover some excuse for the error ; for, 
according to that view, they would not be surprised to find the 
arenaceous formation, now known as Potsdam Sandstone, 
crowning the subjacent masses of slate 
€ may next inquire briefly in regard to the fossil remains 
furnished by these rocks, 
On this branch of the subject I can only speak in the most 
Vermontana, and Conocephalites Teucer. No one of these 
occurs, so far as is known, in any more recent rocks. 
we come to the Potsdam Sandstone we meet with still other 
species. Among the various forms found in this rock I | 
simply cite the Conocephalites Adamsi, C. Vulcanus, and. C. 
minutus. = the several species belonging to this period 
of the next era. But te 
to the Potsdam Group are different from, they are ye 
closely allied to, the species of Conocephalites found in the 
__* [These supposed corals have recently been shown by Prof. 0. C. me 
morganic. This Journal, yol. xly, p. 217.—Eps ] af 
