284 EMMERICH ON THE MORPHOLOGY, CLASSIFICATION | 
(Palaozoic Fossils, London, 1842, and Geology of Yorkshire, 
vol. ii.). 
A thick sandstone and conglomerate formation, the old red, 
deposited in the West and North of England, on the transition 
rocks described, is extremely poor in fossils ; the mountain lime- 
stone, on the other hand, which separates this old red sandstone 
from the coal formation in the more restricted sense,abounds with 
them. Amidst an abundance of Producta, Spirifera, Terebra- 
tula and Crinoidea, some few Trilobites, certainly for the greater 
part in a mutilated state, are also hidden, the last lingering 
representatives of this interesting family. Portlock formed for 
their reception the genera Phillipsia and Griffithides, which have 
already been mentioned when treating of the mountain lime- 
stone of Russia. 
The coal formation is likewise found to be deposited, although 
in a heterogeneous manner, upon the lowest fossiliferous rocks. 
The plants of the former correspond exactly with those of the 
true coal formation ; a subordinate black limestone likewise con- 
tains two Goniatites of the mountain limestone (G. miscolobus 
and crenistria). It can of course not be my intention here to 
treat minutely of the geology of Devon; suffice it to say, that 
we find there a very considerable transition formation, resting 
upon a crystalline rock, overtopped heterogeneously by coal 
formation, its lowest member consisting of clay-slate, its upper 
of a red sandstone slate (grauwacke), with which are interspersed 
several limestones distinguishable by their fossils. Whilst only 
few fossils of the upper Silurian group re-occur in the true 
mountain limestone, there is, on the other hand, a remarkable 
occurrence of the peculiar animals of both formations simul- 
taneously with new ones. Phillips found one-tenth of Silurian, 
one-fifth of mountain limestone species; the remaining seven- 
tenths he ceclares to be peculiar to these Devonshire strata. It 
is not without reason that we presume that a less acute deter- 
miner of species than Mr. Phillips would have detected a con- 
siderably greater number of carboniferous limestone and Silurian 
species among them. But even the facts enumerated justify the 
assumption of Phillips and Murchison, that the transition rock 
of Devon is an intermediate formation between the Silurian for- 
mation and mountain limestone, an equivalent of the old red 
sandstone formed at the same time in other parts of England. 
According to Mr. Phillips, the Trilobites belonging to this 
