TABULAR VIEW. 
25 
it seems more natural to bring all the limestones into the second great division. Throughout 
the region noticed, the upper limestone of the Helderbcrg series, the Corniferous, would 
form a much more obvious termination of the second division. This is every where recogni¬ 
zable, and thence upward to the Carboniferous, the rocks are marked by an entirely different 
assemblage of organic remains. In the Helderberg series, where well developed, the line of 
division, if dependent upon fossils, can be made at one point as well as another ; few of the 
forms rising above the group of which they are typical. 
This arrangement would leave all the shales and thin-bedded sandstones of the succeeding 
groups to form the Third and last division of the System; being a natural lithological assem¬ 
blage, and also pakeontological, if specific characters are considered. 
Another advantage to be derived from this arrangement is, that the great dissimilarity of 
the products of the different divisions would lead to no confusion, as might result if some of 
the limestones are left to be grouped with the shales ; the latter being very meagerly fossilife- 
rous in the west, while the limestones are highly so. 
The middle division would embrace groups exhibiting a considerable diversity of fossil 
characters, yet all possessing forms bearing a generic identity. The different groups, as 
exhibited in the tabular view, with their fossils, to be enumerated in another place, will show 
the character of this division of the system. These three divisions would be easily recognized 
from the great change in lithological character, as well as extinction of fossil species, at the 
termination of each one. 
Geol. 4th Dist. 
4 
