156 A general Review of the Geology of Russia. 
schiefer, zechstein, and the sandstones of the Vosges. Since 
this formation is much more developed in Russia than elsewhere, 
and at the same time, since the beds do not present the same or- 
der as in Germany and England, the authors have thought proper 
to give it the name of the Permean system, upon the same prin- 
ciple that other paleeozoic formations have been named from the 
country where they are most complete and best developed. 
assing to the secondary formations, M. de Verneuil pointed out 
the difficulties which are experienced in Russia in recognizing 
the true representative of the triassic formation. Judging from 
the few fossils which Count Keyserling found on Mount Bogdo, 
there is reason to believe that that formation exists in the Russian 
empire ; and it is not impossible, that certain red sandstones or 
marls of the Government of Orenburg and Vologda represent the 
“ bunter sandstein.” 
If the trias has almost disappeared in Russia, the Jurassic for- 
mation, on the contrary, is easily recognized by its fossils. C= 
cupies a considerable area, and the authors traced it through the 
xovernments of Trer, Moscow, Valadimir, Simbirsk, Saratof, 
where it forms a vast basin of which the different parts are for 
the most part continuous. Another basin extends to the border of 
the Volga by Kastroma nearly to the eastern limit of the govern- 
ment of Vologda, towards the side of Ust-Sisolsk. Lastly, the 
same formation constitutes the surface of a great part of the 
“toundras” or marshy plains of the basin of the Petchora and of 
the Frozen Ocean. In central Russia the inferior part is com- 
posed of pisolite beds which enclose subordinate beds of blue ar- 
gillaceous limestone. ‘T'he superior part consists of a quartzose 
sandstone of considerable thickness and of a bluish grey color, 
generally non-fossiliferous, in which, nevertheless, some plants 
and mo! have, recently, been discovered. It is remarkable 
that the Ammonites cordatus and several other fossils of the age 
of the Oxford clay are found in the lowest beds; so that the lias 
and the inferior oolite seem to be absent. A considerable por- 
tion, therefore, of the series is absent ; this is the more important 
to be observed since it establishes the deficiency of strata which 
follow upon the trias, a formation, the existence of which: in 
Russia is still problematical. 
The cretaceous formation is found in Russia, only on the south 
of the Devonian axis which traverses the central part of the Em- 
i It is one of the most extensive formations of the southern 
governments, but it does not extend north of the government 
Simbirsk. It occupies a considerable zone on the side of the 
Uralsk, and extends also into the Crimea, M. de Verneuil re- 
marked orton ath that, in this immense country, the eretaceous 
series is always represented by white limestone with silex, grey 
limestone, siliceous argil and sandstone, possessing, therefore, all 
