Chap. XIV.] 
DEVONIAN EOCKS OF EUSSIA. 
363 
in the same hand-specimens frequent examples of typical Devonian Mollusca 
together with Old Red Ichthyolites like those of Scotland *. 
A similar intermixture has indeed been since recognized, to some extent, in 
the Devonian rocks of South England, the Eifel, and the Harz, and also in North 
America. 
The progress of research had enabled M. Kutorga to divide the Devonian 
rocks of a part of Russia into three stages, in the ascending order — of clay and 
marl with Lingula bicarinata, compact sandstone with many Ichthyolites, and 
argillaceous limestone with many Brachiopods. M. Pander, in the notice pre- 
viously referred to, has even shown that the highest of these beds is covered by 
other sandy strata, in which fossil Fishes of the Devonian epoch equally abound. 
This author also distinguishes three stages in the Devonian rocks of Russia. 
The lowest consists of sandstones and shale, with those Ichthyolites which 
abound in the north of Livonia and the environs of Dorpat and Tellin : these 
are the Fishes which Asmus made known, and which Pander described in his 
First Fasciculus as Devonian Placoderms. In these beds Shells are rare ; but 
the Lingula does occur, and its presence alone clearly shows that the associated 
Fishes were also inhabitants of the sea. These strata contain the same Fishes 
as the Caithness beds of the North of Scotland. The next stage, consisting of 
limestones, both dolomitic and simple, and of shales, is laden with marine Mol- 
lusca, which are mixed up in the same beds with various Ichthyolites, and ex- 
tend over wide spaces. In this zone, as General Helmersen informs me, Pro- 
ductus productoides, Terebratula Livonica, Spirifer Archiaci, Sp. Anosoffi, and 
many other Shells, with Corals and Encrinites, are often commingled with re- 
mains of Holoptychius nobilissimus, and numerous bones and plates of other 
Fishes which Pander has described. This is manifestly one of the stages of the 
Old Red Sandstone of Scotland, the Holoptychius and other Fish-remains of 
which are thus proved to be of marine origin. 
The third and highest stage, consisting of reddish sands, occasionally with 
green marls, seems to be simply an upward continuation of the band below it, 
and contains also some of the same Holoptychius with other Fish -remains. 
In the more southern tracts near Voroneje f , it was shown, by myself and 
associates (and the phenomenon is now known to prevail in many other tracts), 
that many species of marine Brachiopods were commingled with Fishes in one 
and the same marly stratum. It follows, therefore, that the minute distinctions, 
lithological and organic, traceable in one district are riot applicable to another, 
and that the limestones are mere local deposits in a great arenaceous and marly 
series of strata j whilst, on the whole, the identification of the group with its 
equivalents in other parts of the world has been established in the clearest 
manner by means of the fossil contents. 
Reposing, as a whole, on the Uppermost Silurian in Esthonia, and on Lower Si- 
lurian in the Government of St. Petersburg, the upper members of these Devonian 
strata are in numberless places overlain conformably by, and pass up into, Car- 
boniferous Limestone. In some tracts the strata consist of flag-like shelly 
limestones and marls, in others of sandstones both soft and hard, which range 
over extensive northern districts to the banks of the Lake of Onega and the 
shores of the White Sea. 
* I can also cite with satisfaction another con- 
firmation of my views, as conveyed in a letter I 
received from so high an authority as Pander, 
who wrote thus : — " The Devonian rocks, which 
are so clearly described in your work that one 
could almost find them in the dark, have attracted 
my particular attention on account of their Fishes ; 
for by these remains, together with the charac- 
teristic Brachiopoda and Acephala, the agreement 
of the rocks of this system in Eussia and Britain 
is shown in the clearest way." — April 1658. 
t ' Eussia-in-Europe,' p. 60. 
