360 Parallelism of the Paleozoic Deposits 
no other means than to study in each of them a series of beds 
comprised between two known and well determined points, to 
compare their fossils, to seek out the identical species, and to see 
if these species are distributed according to the same law. If it 
happens that in the two countries a certain number of systems, 
characterized by the same fossils, are superimposed in the same 
order, whatever may be, otherwise, their thickness and the num- 
ber of physical groups of which they are composed, it is philo- 
sophical to consider these systems as parallel and synchronous. 
This is precisely what we intend to do in this place. The 
sections of sedimentary deposits which we will compare in the 
two countries, comprise the most ancient fossiliferous beds, an 
extend to those which contain the coal. They are of equal. 
value; and if we succeed in establishing, that there exists in 
America a certain succession of systems or stages disposed as in 
Europe, and characterized by the same fossils, we shall have, it 
pee 
cupy corresponding positions. It is this which gives to Paleo- 
zoic characters that generality of application which constitutes 
their value, and this is also, the easiest part of our task. 
e series of Paleozoic deposits, being, as we have said, more 
complete in America than in Europe, the comparison which we 
shall endeavor to make, may throw light upon some contested 
points of European classification, and furnish certain links which 
are wanting to us. . 
The comparison of Europe with North America will have still 
this great advantage, of determining, among the groups of wh 
each of our systems is composed or each of the great divisions 
of the Paleozoic formation, those which have the greatest 1m- 
portance by their constancy and the facility with which they are 
recognized in all countries. We shall thus see that these groups 
are, in the inferior stage of the Silurian system, the Orthoceratite 
limestone of Sweden and Russia; in the superior stage, the 
limestones of Wenlock and of Gothland; in the Devonian sy® 
tem, those of the Eifel, of Brittany, of Devonshire, etc. etc. . 
a ea Te, eee 
