DEVONIAN AND OLD RED PERIOD. 133 
series is a great system of deposits, to which the name of “ Old 
Red Sandstone” was originally applied, to distinguish them 
from certain arenaceous strata which lie above the coal (“ New 
Red Sandstone”). The Old Red Sandstone, properly so 
called, was originally described and investigated as occurring 
in Scotland and in South Wales and its borders ; and similar 
strata occur in the south of Ireland. Subsequently it was 
discovered that sediments of a different mineral nature, and 
containing different organic remains, intervened between the 
Silurian and the Carboniferous rocks on the continent of Eu- 
rope, and strata with similar paleontological characters to these 
were found occupying a considerable area in Devonshire. The 
name of “‘ Devonian” was applied to these deposits ; and this 
title, by common usage, has come to be regarded as synony- 
mous with the name of ‘Old Red Sandstone.” Lastly, a 
magnificent series of deposits, containing marine fossils, and 
undoubtedly equivalent to the true “ Devonian” of Devon- 
shire, Rhenish Prussia, Belgium, and France, is found to inter- 
vene in North America between the summit of the Silurian 
and the base of the Carboniferous rocks. 
Much difficulty has been felt in correlating the true ‘‘ Devon- 
ian Rocks” with the typical “Old Red Sandstone”—this difh- 
culty arising from the fact that though both formations are 
fossiliferous, the peculiar fossils of each have only been rarely 
and partially found associated together. The characteristic 
crustaceans and many of the characteristic fishes of the Old 
Red are wanting in the Devonian; whilst the corals and 
marine shells of the latter do not occur in the former. It is 
impossible here to enter into any discussion as to the merits 
of the controversy to which this difficulty has given origin. 
No one, however, can doubt the importance and reality of ‘the 
Devonian series as an independent system of rocks to be in- 
tercalated in point of time between the Silurian and the Car- 
boniferous. The want of agreement, both lthologically and 
palzontologically, between the Devonian and the Old Red, 
can be explained by supposing that these two formations, 
though wholly or in great part contemporaneous, and therefore 
strict equivalents, represent deposits in two different geographi- 
cal areas, laid down under different conditions. On this view, 
the typical Devonian rocks of Europe, Britain, and North 
America are the deep-sea deposits of the Devonian period, or, 
at any rate, are genuine marine sediments formed far from 
land. On the other hand, the ‘Old Red Sandstone” of 
Britain and the corresponding ‘‘Gaspé Group” of Eastern 
