528 Geological Society: Anniversary Address, 1843. 
the springs and currents, and the depth of the seas in which they 
were accumulated *.” 
Devonian Rocks.—If the horizontal range of the Silurian rocks of 
Russiabe considered large as respects our terms of comparison, what 
will my associates say to the expanse over which the Devonian or next 
ascending group is spread, when I tell them that it is much larger 
than the whole of the British Isles? Reposing upon the low Silurian 
plateaus, this widely ranging deposit rises to heights of from 500 to 
900 feet above the sea; and it is very remarkable by being charged in 
many localities with ichthyolites, several species of which, hitherto 
considered peculiar to the Scottish Old Red Sandstone, are found 
associated with Mollusks, perfectly similar as a group, and often 
specifically the same, as those of the limestones of South Devon, 
the Boulonnais and the Eifel. The discovery of the intermixture 
of Scottish Old Red Sandstone fishes and true Devonian shells in the 
same strata, was, you may believe, one of the most gratifying results 
of the recent explorations in Russia, as being confirmatory of the 
views of Professor Sedgwick, Mr. Lonsdale and myself respecting 
the divisions and equivalents of that member of the Palzeozoic Rocks. 
In some parts of Russia, the Devonian rocks are red sandstones and 
marls ; but in an extensive central tract, where they rise into a dome 
which separates the northern from the southern basin of the em- 
pire, they are composed of yellow sandy marls and limestones, which 
lithologically might be mistaken for the magnesian limestone beds of 
our northern counties :—so inapplicable are mineralogical terms as 
marks of geological epochs. 
In the vastness of their undisturbed and nearly horizontal extent, 
these strata afford us most instructive proofs of the intimate con- 
nection between the stony condition of the rocks and the imbedded 
fossils; for, when the calcareous matter is present, various mollusks 
are associated with some fishes, whilst in those tracts where the lime- 
stones disappear and the beds have the characters of the Old Red 
Sandstone of Scotland, fishes only can be detected : thus presenting 4 
remarkable analogy between the distribution of this very ancient 
fauna and that of existing nature; the present great receptacles of 
fishes being deep sandy bottoms, whilst shelly creatures congregate 
towards the shores where calcareous springs attract them. I shall 
elsewhere allude to the fishes of this deposit when speaking of the 
researches of Professor Agassiz. 
Carboniferous Rocks.—The Carboniferous deposits, which succeed, 
cover an area as broad as that of the Devonian or Old Red rocks ; 
and they are throughout clearly distinguished by a decidedly di- 
stinet type of animal life, presenting in some families an extraordi- 
nary number of species absolutely undistinguishable from those of 
our own country published in the works of Sowerby and Phil- 
lips. This system is eminently calcareous, and exhibits a vast 
marine succession, in which the fossils of the Mountain Limestone 
* Geological Researches in Russia (in the press) by Roderick Impey Mur- 
chison, E. de Verneuil, and Count A. von Keyserling, assisted by Lieut. 
Koksharof, p. 40. 
