380 Murchison’s Siluria. 
Dr. Owen’s Report are too imperfect to allow of their generic posi- 
tion being fixed with certainty. Barrande also discovered ona 
specimen of the St. Croix sandstone a Pteropod nearly allied to 
the Pugiunculus primus of his primordial Fauna. to these 
the Lingula, and the closely allied forms of Orbicula and Obolus 
and we have, with the fucoids of the Lake Superior and New 
York sandstones, a fair representation of the primordial Fauna. 
The unity of the system of organic life below the coal is very 
evident, and the great difference of opinion as to where the lines 
dividing the whole palzozoic series into groups ought to be drawn 
proves sufficiently the difficulty of breaking up the system into 
arts. The Devonian System was proposed by Sedgwick and , 
Murchison about the same time as the Silurian, and embraced a 
series of rocks intermediate in position between the upper Silurian 
and the Carboniferous. The fine-grained limestones and slates of 
Devonshire were regarded by these geologists as contemporaneous 
with the Old Red Sandstone of Scotland, the rocks of Devon and 
Cornwall containing shells and corals of both Upper Silurian and 
Carboniferous types, while the Old Red is rich in fossil fishes. We 
have in this country fonnd it very difficult to reconcile our geol- 
ogy with the views generally adopted in England in regard to 
the Devonian. As has been shown by James Hall, our forma- 
tions can with difficulty be brought into parallelism with those 
of England, as long as the systems and groups remain with the lim- 
its which they have generally been regarded as having among the 
geologists of that country. The latest investigations, however, 
seem to have thrown new light on this subject and when the de- 
tailed examination of the groups in the south of Ireland which 
are intermediate between the Carboniferous and the Lower Silu- 
rian shells have been’ published, we may hope to be materially 
aided in our comparisons. At present, Mr. Sharpe considers the 
South Devon limestones as the exact equivalent of the limestone 
of the “Systeme Eifelien” of Dumont* and therefore above the 
Old Red Sandstone. he Eifelian is intermediate between the 
Condrusian and Ahrian systems, of which the former is repre- 
sented in England by the Carboniferous series together with the 
Culm measures of Devonshire, including the Petherwin and ¥° 
ton beds, which Mr. Sharpe removes from the Devonian to the 
Carboniferous. The Ahrian and the next inferior system, the rb- 
lenzian, which are intermediate between the Old Red Sandstone 
and the Silurian, have not been recognised in England, but are 
considered to be represented in New York by the rocks between 
the Oriskany sandstone and the sandstone and shales of the Vats- 
kill Mountains. In the Devoniag, as at present limited 10 Eng- 
land, the proportion of Silurian and Carboniferous species 18 5° 
in! team io his word fr sytem ns tunly wndersood 
