352 Subdivisions of the Paleozoic Strata of Great Britain. 
the continent (e.g. those of the Rhenish provinces) seem to run 
into an intimate union with the Silurian. Hence it appears to 
me by no means improbable that we may be hereafter induced 
{ provided we continue to separate the whole Paleozoic system, 
as in the Tabular View, into three primary sapernnge' to place the 
Silurian series not in the dower, but along with the Devonian 
series in the middle division of Paleozoic rocks. I rn throw 
this out as a mere hypothesis; and if it be hereafter adopted, it 
must be on a wider base of evidence than is at present supplied 
by the Paleozoic system of England. 
Thirdly. Though the Devonian series, of the Herefordshire 
is generally a paleontological and physical gap between, them, 
which is in many places obscurely indicated by the upper con- 
glomerates of the old red sandstone. Now this gap is, if I mis- 
take not, filled up by the higher Devonian groups in Cornwall 
and Devonshire. In those counties, when we draw a line be- 
tween the Devonian and Carboniferous rocks, we find the physi- 
cal and paleontological evidence in positive conflict. For if we 
go on the single iio of counting species the Petherwin and 
Barnstaple groups (as was, I believe, first pointed out by 
Griffith on the specific pei a ak Professor McCoy ) oa 
be packed with the Carboniferous series. But in so doing we 
deprive of all importance a grand group of dark slates and flags, 
which seem to have been laid down by nature’s hand as the true 
and continuous base of the great Culm-trough of Devonshire 
Cornwall. Nor is this all. The Petherwin and Barnstaple 
groups, along with many true Carboniferous types, conta in sev- 
eral genera and species which have not hitherto been considered 
as Carboniferous. In such acase as this we may strike a balance 
in oe conflicting weight of evidence offered by the groups, by 
ing them an undefined margin, and by adopting a provisional 
Bi conclatiar: ~g 
* The case of the Old Red sandstone of the north of England has not been prom- 
inently noticed. It generally appears (as above stated) in ‘the form of a beret 
, which, if I mistake not, represents only the part of the Devo- 
In following the base of the Carboniferous rocks (as they wind round 
n the neighborho per 
are perfectly can ny to the overlying beds of the great scar-limestone. Nor 1s this 
all. Beds of red sandstone, of an identical mineral type, alternate, in thick masses, 
thence 
there ye obviously an intimate union between the Old Red and Car- 
us series—a fact hich seems to sanction the opinion that the Old Red com 
giomeraie of the north of gla d represent only the upper part of the Devonian 
