180 Parallelism of the Paleozoic Deposits 
There is very good reason for uniting the Trenton limestone, 
Utica slate, and Hudson River group; for although the middle 
term contains few fossils of any species, yet several are common 
to the three terms, and of those known in the Trenton limestone, 
twenty species reappear in the Hudson River group. M. de Ver- 
neuil has become satisfied of the fact, that these groups form but 
a single one at the west, scarcely distinguishable into the three 
divisions which are well marked in New York. Notwithstand- 
ing there are in the Hudson River group several species of Gas- 
teropoda and Acephala, quite distinct from those of the Trenton 
limestone, yet the species of Brachiopods are identical ;—not more 
than two species appearing at this period which are not also com- 
mon to the ‘Trenton limestone. 
In the description of the succeeding rocks, M. de Verneuil very 
properly suggests that the Oneida conglomerate and grey sandstone 
should form the base of the succeeding division, rather than re- 
main united with the Hudson River group in the Champlain di- 
vision. ‘This course has already been followed in the Paleonto- 
logical report,—the first, great division being regarded as ending 
with the Hudson River group, at which point the greater part of 
those species regarded as belonging to the lower Silurian epoch, 
terminate their existence. 
It is not necessary to follow our author through all the succes- 
sive groups, since the principal object is to arrive at his results. 
In the second period of our system, he suggests a union of the 
water-lime, the Pentumerus galeatus limestone, the lthyris 
shaly limestone, and upper Pentamerus limestone, as one group. 
In this not only do we readily acquiesce, but are happy to be sus- 
tained in what we have already done in effect, by so able and im- 
partial an observer as M. de Verneuil. These subdivisions are 
no where perfectly discernible except in the eastern part of New 
York, and here it is quite evident that they are united by their 
organic contents, although slightly different in lithological char- 
acter, and each bed showing a predominance of certain forms, to 
the almost entire exclusion of all others. Our author remarks, 
that the lower of these four groups rests upon the Hudson River 
group, at Schoharie, which, though generally very nearly true, is 
not precisely so, there being a partial representation of both the 
ondaga salt group and Niagara group, as we have had occasion 
to show elsewhere. 
M. de Verneuil proposes to unite the Caudagalli grit with 
Schoharie grit, and the Onondaga with the corniferous limestones. 
A more natural arrangement, and one which the organic contents 
compel us to follow, is to unite the Schoharie grit, the Onondaga 
Birdseye passes into the Black River li 5 whi 
Pipi 7 ee ne E ns Riser limestone ; while an equal number meee? 
