FERRUGINOUS SANDS AND GRIT WITH PLANTS. 
241 
It would further appear that Professor Rouiller, of the Imperial Academy of Moscow, 
has examined the substance of this rock very carefully under the microscope, and 
has discovered in it an extraordinary quantity of siliceous sheaths of Infusoria, 
among which, besides some unknown genera, he has recognised Bacillaria, Fragil- 
laria, Cosconema, Galionella, &c. 
Regretting that we have not had it in our power to inspect the remains of the 
fishes, infusoria and plants, from the last-mentioned locality, we still think that we 
can form a tolerably correct decision as to the age of these beds, from the drawings 
of the plants of Tatarova and Klin only, when coupled with our personal acquaint- 
ance with the succession and relations of the strata. It is, indeed, quite evident 
that these plants, for the most part Cycadese and Ferns, with fragments of stems, 
which, if not those of Calamites, probably belong to Zarnise, are from their facies 
of at least as high antiquity as the upper and middle oolite, and having referred 
them to Dr. Mantell and Dr. Lindley, those competent authorities are of opinion 
that they more natui'ally pertain as a group to the Flora of the Jurassic than to 
that of any other system. No such plants have ever been found in Cretaceous 
l’ocks, and it is needless to add that they are wholly unlike any forms of vegetation 
of the Tertiary age. 
The geological relations of the strata in which the plants are contained, are com- 
pletely in accordance with this view ; for we have shown that they constitute the 
conformable roof of beds with many Oxfordian shells, and that in one locality (the 
Sparrow Hills), the latter are seen to pass upwards into white and ferruginous 
sands scarcely to be distinguished from those of Tatarova. 
We shall afterwards point out other sections on the Volga where a similar 
ascending order is observed, and where, as at Moscow, it is impracticable to sepa- 
rate the overlying iron sands from the inferior Ammonitic shales ; and towards 
the close of the chapter we shall indicate how in the south of Russia, sands, with 
plants and lignite, which we believe to be similar, are overlaid by limestones ot the 
age of the Coral Rag. 
A recent excursion to Poland, to which allusion has been made when treating of 
the Permian rocks, also enables us to throw collateral light on this question. 
By reference to the geological map of Poland by M. Pusch, it will be seen that he 
considers a large tract of sandstones between Warsaw and Kielce to be either of 
the eera of the lower Lias ( Gres du Lias), or of the Keuper. Having previously con- 
vinced ourselves that there were no representatives of the Lias or Keuper in the 
