of the Northern and Central Begions of Russia. 133 



any litliological equivalents for the British old red system, yet, that, in 

 extending researches far to the east, this member 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 many other places, is 

 seen to overlie the old red sandstone. The inferior beds consist of in- 

 coherent sandstones and bituminous sliale, which sometimes contain thin 

 beds of impure pyritous coal, and impressions of several plants well 

 known in the carboniferous system of our own islands. These are sur- 

 mounted by various bands of limestone, the lowest of which only have 

 occasionally some mineralogical resemblance to the mountain limestone 

 - of Western Europe ; other beds being lithologically undistinguishable 

 from the magnesian limestone of England ; some from a pisolite ; a third 

 and very prevalent band of considerable thickness is milk-white, and not 

 more compact than the calcaire grossier of Paris. This white Productus 

 limestone was traced by the authors from the neighbourhood of Mosco%V 

 to beyond Archangel (and they ascertained that it ranged far into the 

 country of the Samoiedes), a distance of not less than 1000 miles. This 

 formation has also a mineral resemblance to chalk, in being loaded with 

 thin bands of flints, sometimes concretionary, in which shells and corals 

 occur. Associated with this formation, on the banks of the Dwina, 

 about 200 wersts above Archangel, and south of Siisskaia, are splendid 

 bedded masses of white gypsum, which for many miles present, at a little 

 distance, all the appearance of Avhite limestone.* With these grand 

 gypseous deposits in which are occasionally large concretions, two or three 

 thin bands of limestone alternate, in one of which the authors detected 

 fossil shells (Avicula) which are new to them. Other peculiar bands 

 near Ust-Yaga, which are rather higher in the series, contain a Productus 

 approaching to P. scabriculus, with pectens and corals. 



The carboniferous limestone of Russia is highly fossiliferous, and from 

 the normal and unaltered condition of most of the beds, the fossils are 

 generally in an excellent state of preservation. Among them are many 

 well-known British species, the lower beds being distinguished by the 

 large Productus hemisphceoicus so well known in the same lower beds of 

 England and Scotland ; and the white beds being loaded with many of 

 the species published by Fischer, Phillips, antl Sowerby, such as Pj'O- 

 ductus Martini, P. puncta'us, Sanguinolaria sulcata, Spirifer Mosquensis, 

 Cardium alceforme, Cidaris vetustus, together with the abundant and cha- 

 racteristic Russian coral, Cheetites radians (found, according to Mr Lons- 

 dale, in the carboniferous limestone of Bristol, &c.), and the Lithostrition 



* See M. Rolxjrts's.aecpuntTqf these white cliffs, which he supposed io W 

 Hm9siQlk9*^J3nlktin d€ la SifCt G.€ol d€ France, \B40, ,. 



