348 Subdivisions of the Paleozoic Strata of Great Britain. 
The Petherwin (or Barnstaple) group is provisionally arranged 
in the Devonian series. Physically, it is best connected wit 
the older groups of Devonshire and Gosnell ; but paleontologi- 
cally, it is perhaps better connected with the rocks of the Upper 
Paleozoic division.* Here, therefore, there seems to be a con- 
tinuous ascending order of deposits, and a passage from the De- 
vonian series to the Carboniferous. 
(3.) Devonian Series of Scotland. 
Grand as is the development of the Old Red Sandstone of 
Herefordshire, it dwindles into insignificance when compare 
with the rocks which pass under the same name in Scotland. 
They are divided by Miller as follows :— 
(1. Great conglomerate and red sandstone. 
2. Bituminous Se samrat tea Sdn Pterichthys, Coecosteus, &e. 
a 3 Red ane ee ed sanidston 
2 Thes ee grou pe ae ouitke up the “lower formation” of Miller, and are well 
o seen im Ca ithne: 
% | 4, Gray sacatone poor slates, &c. This is the “ middle formation” of Miller, 
4 
BI and ¢ a peculiar group of fishes, Cephalaspis, &ec. 
s 5 Red san ites and conglomer. te. 
2 pure concretionary limes 
A} 7. Yellow siliceous meh ne. ; 
st three, called by Miller the “upper formation,” are characterized 
a by Hatephjahichs: &e. 
This vast North-British series has no true palzeontological base ; 
but its “upper formation” seems to graduate into the Carbonifer- 
ous series. 
Its lower groups have no known representatives in the or 
Red Sandstone of Herefordshire, and cannot (with our present 
information) be drawn into a close and unequivocal comparison 
with the “ tilestone” and fish-beds of the Ludlow rock. But its 
“middle and upper formation” seem to be represented, though 
imperfectly, by the ceeear a and overlying conglomerates, 
. of Herefordshire. From this also it seems to follow, that 
the npper part of the Old Red Sandstone of Herefordshire is de- 
fective in its development; and the conglomerate form of its 
upper beds appears to sanction the conclusion. If this conclu- 
sion be received, it will follow that the Devonian series of Here- 
fordshire is defective at its upper extremity, while the same series 
in Devon and Cornwall is defective at its base. 
But if we take the Devonian series of Scotland as our type, 2 
still more remarkable conclusion seems to follow: viz., that the 
This nestion is Giciaed Sag ioe the Slate Rick of Deon and Com 
“Risse Siundd oF Oc. Bae tal ig 1852." 
