401 
true equivalents of the Silurian system, was determined not only by 
their aspect and fossil contents, but by their being overlaid by other 
rocks which are completely identical with the ‘Old Red System ”’ 
of the British Isles, as defined by Mr. Murchison*. This system is 
of great extent in Russia. It passes from Livonia by the lakes of 
Ilmen and the Waldai Hills, and is extended over a vast region to 
the N.E., where it constitutes a large portion of the shores of the 
White Sea. This system consists of flagstone, clays, marls, corn- 
stones and sandstones, the whole bearing a considerable resemblance 
to some red deposits of the same age in our isles, but differing by 
containing copious salt. springs and much gypsum. It was the oc- 
currence of so much salt and gypsum that led previous writers to 
consider these deposits an equivalent of our new red system, which, 
being found to conta the same minerals in the western parts of 
Europe, had been even termed by some, the saliferous system. That 
the red deposits (red and green) are, however, the true equivalents 
of our old red sandstone, is demonstrated, not only by order of 
superposition, but also by the many organic remains which they 
offer. Fishes are the most distinguishing fossils of this great Rus- 
sian system, and among these are species (notably the Holoptychius 
Nobilissimus, Murchison, with the Coccosteus, Diplopterus and Cteno- 
ptychius of Agassiz), forms which occur in deposits of the same age 
in Scotland. ‘The fishes are in abundance, and a work, illustrative 
of them, is now preparing by Professor Asmus, of Dorpat, near which 
University they abound The authors have traced these fish-beds 
for a great distance, occupying several stages in the system, and 
each stage characterized by péculiar species of ichthyolites. 
The zoological contents of this system are also of great value in 
illustrating and confirming the palzozoic classification proposed by 
Messrs. Sedgwick, Murchison and Lonsdale; or in other words, the 
evidences found in Russia leave no doubt that the old red and De- 
vonian systems of rocks are identical. The Orthis subfusiformis, O. 
striata, Spirifer calcarata, S. trapezoidalis, Productus caperatus, Te- 
rebratula prisca (large var.), and Serpula omphaloides, shells distinct 
from those of the carboniferous system, but similar to those which 
occur in Devonshire, Westphalia, Belgium, and other places (in de- 
posits which have been shown by these authors to be of the age of 
the old red sandstone), are found in Russia in the same beds with the 
fossil fishes of the old red sandstone of the British Isles. 
Still more striking, observe the authors, are these cumulative 
proofs, when it is stated, that although in France and Germany 
there are scarcely any lithological equivalents for the British old red 
system, yet, that in extending researches far to the east, this mem- 
ber of the series is found to resume very many of the same mineral 
characters which distinguish it in the central and northern parts of 
the British Isles; and then under similar conditions it contains the 
ichthyolites of the British deposits. 
3. Carboniferous System.—In the northern regions of Russia, the 
lower or calcareous part only of the carboniferous system exists, 
which in the Waldai Hills, near Wytegra, on the Onega, and in 
* See Silurian Researches, p. 165, and ‘Table with the Map. 
. 
