RESUME AND CONCLUSION. 
581 
development of the Russian strata of this age has further dispelled all doubt con- 
cerning the identity between the Old Red Sandstone of Scotland with its ichthy- 
olites, and the slaty, calcareous rocks of Devonshire and the Rhenish provinces 
with their shells and corals, since it exhibits innumerable proofs, that the fishes 
and mollusks, which in most parts of western Europe appear to have been severally 
peculiar to smaller detached basins, were in this region living in the same sea, 
and entombed in the same beds. Here also, as in the Silurian rocks, we perceive 
a marked connection between the mineral character of this deposit (which occupies 
so vast an area in Russia) and its imbedded fossils ; for in certain great sandy tracts 
of that empire, as in the Scottish Old Red Sandstone, its organic remains are 
exclusively those of fishes ; whilst in districts, where calcareous and diversified 
strata occur, similar species of fishes are associated with mollusks and other 
organic bodies. 
Ascending to the third system, it has been shown, that a very large portion 
of Russia is occupied by limestones and associated shales and sands, which, 
from their fossils, are completely assimilated to the carboniferous or mountain 
limestone of other well-known countries. Trilobites, extremely abundant in the 
Silurian and rare in the Devonian strata, become very scarce in this deposit ; and 
though ichthyolites, including some of peculiar sauroid forms, are abundant in 
this formation in England, Belgium and France, they seldom occur in Russia ; a 
scarcity which may have depended on the absence of favouring submarine condi- 
tions. Brachiopods entirely different from those of the subjacent formations, con- 
stitute, in truth, the great and general terms of distinction ; many of the species 
being absolutely the same as those of the like age in the British Isles, even when 
the deposit is followed into the low countries of Siberia. In the regions under 
review T , as elsewhere, these carboniferous rocks are the lowest receptacles in which 
numerous land plants have been found, and these vegetables also are often un- 
distinguishable from those which occur in similar beds of western Europe. These 
and other examples observed at Melville Island, the north coast of America, in 
Spitzbergen and Nova Zemlia, as well as in the more southern latitudes of Europe, 
have led us to believe, that in all those ancient periods, when the same species of 
shells lived in seas distant from each other upwards of 4000 miles, and when 
the first tree-bearing lands, whether Arctic or equatorial, produced the same great 
monocotyledonous plants (the source of all great coal-fields), there must have been 
4 F 
i 
