134 
CARBONIFEROUS FAUNA OF RUSSIA. 
plained on the principle of certain peculiar submarine conditions, to which allusion 
has already been made (see p. 64). The few which have been discovered, including 
a fine ichthyodorulite 1 and some small teeth, are, however, quite distinct from the 
remains of fishes of the preceding period. Trilobites, so profuse in the Silurian 
epoch, and so very rare in the Devonian, are also but little developed in the car- 
boniferous age ; two small species only having been found, which are very closely 
allied to the trilobites of the mountain limestone of England and of Belgium. A 
Cytherina, or minute marine crustacean, also found in those countries, has been 
detected at two or three places in Russia, where, as will have been observed, the 
genus is not limited to rocks of this age, but commencing life in the later days 
of the Devonian epoch, its existence was prolonged, as will hereafter be shown, 
into deposits of the age of the Zechstein. 
The Cephalopoda, so numerous and of such varied forms in the carboniferous 
deposits of the West of Europe, are, on the contrary, very rare in Russia. Of 
Orthoceratites we are as yet acquainted with two or three distinct species only, and 
Goniatites, unknown throughout the great mass of Russia in Europe, are found 
in certain upper strata only, on the flanks of the Ural chain. To some of these 
we have already alluded, as existing in the grits of Artinsk, but when we come 
to explain the structure of the Ural, and to show the nature of the carboniferous 
limestones on the Asiatic side of that chain, it will then appear, that at a spot 
distant upwards of 2500 miles from the British Isles, Goniatites are there found 
(with many other shells) absolutely identical with those of the English and Belgian 
carboniferous rocks. The Nautili are as scarce as other Cephalopods. We iden- 
tified, however, the N. tuberculatus as common to the Ural mountains, Vitegra and 
the Valdai Hills ; and the country of the Donetz affords the Nautilus Leplayi 
(Nob.). Bellerophons are indeed pretty plentiful, but, for the most part, their 
shelly matter has disappeared, and they are to be observed in the form of casts 
only. A good exception to this remark is that in the Valdai Hills, the Belle- 
rophon clathratus (D’Orb.) and B. depressus (Eich.) were both found in complete pre- 
servation, the former being undistinguishable from British and Belgian species. 
The Brachiopods, and particularly the Producti, abound to such an extent, that 
the mountain or carboniferous limestone, here as elsewhere, might well be called 
“ Productus Limestone.” And what is still more remarkable, the species are almost 
1 This ichthyodorulite was found by Colonel Helmersen, 
