357 



of some of the sandstones of North America, generally 

 considered as the Old Red Sandstone. 



Some of these had heen designated hy Mr. Marcou as Triassic, 

 and he showed by characteristic calamites that the strata so named 

 by the latter in New Brunswick were properly so called. The 

 calamites exhibited from the strata of southern New Brunswick 

 had a more elongated stem, fewer vertical furrows, and a greater 

 distance between the joints, than the Carboniferous and Devonian 

 forms, and had the aspect of Triassic calamites. He thought the 

 New Brunswick fossils were different from the C. arenaceus of 

 the Trias of Europe. 



Mr. Marcou made a communication on the black slate 

 of Braintree, Mass., containing Paradoxides, and on simi- 

 •lar strata in Newfoundland, near Lake Champlain, and 

 in the vicinity of Quebec. 



The Braintree slate contains trilobites, and a Conocephalus has 

 been discovered in the same formation in Newfoundland ; here are 

 two remotely separated points in North America, whose fossils 

 indicate an age anterior to the Silurian, belonging to what Bar- 

 rande calls the faune primordiale. Prof. James Hall found near 

 Lake Champlain three trilobites in strata which he referred to 

 the Hudson River group, or to the second fauna of Barrande ; 

 others obtained near Quebec were referred to the same group by 

 Mr. Logan ; and this whole chain of rocks has been referred by 

 these and other geologists to the Hudson River group. Emmons 

 long ago discovered these rocks in Vermont, and called them the 

 "Taconic System;" this is equivalent to the primordial fauna of 

 Barrande, and Emmons's name, given in 1846, four years before 

 that of Barrande, should be substituted ^ov faune primordiale. 



The trilobites found near Quebec were obtained from the rocks 

 at the Falls of Montmorenci ; at the surface here is a horizontal 

 limestone belonging to the Trenton group, and the rock which 

 forms the falls is gneiss ; below the falls are the black shales, very 

 much upheaved, going back fifteen or twenty miles into the country, 

 and indicating an immense thickness ; Mr. Marcou had no doubt 

 that the fossils were found in these shales, which are anterior to 

 the limestone. The Potsdam sandstone, in New York, had until 



