532 Geological Society: Anniversary Address, 1843. 
Agreeing in the correctness of the general parallel which M. Le 
Play has drawn between the deposits of the Donetz and the carbo- 
niferous limestones of Great Britain, Belgium and France, I do not 
believe that beyond this point his comparisons can be sustained. 
The coal fields, for example, of the Low Countries and of Diussel- 
dorf, with which I am well acquainted, do not offer, as he supposes, 
an analogy to those of the Donetz; for in the former, coal-seams are 
in no instance interstratified with the Mountain Limestone series 
of English geologists, but are invariably superposed to it. Again, 
in the Prussian and Belgian provinces, the mountain limestone with 
sands and shale but void of coal, reposes on a fine succession of 
Devonian and Silurian rocks, loaded with typical fossils; whilst 
the group of the Donetz, exclusively carboniferous to its base, 
rests at once either on very ancient crystalline rocks, or upon por- 
phyries and other eruptive masses, to the agency of which is to be 
attributed the extraordinary contortions into which the strata have 
been thrown. The true analogy, therefore, of the coal of the Do- 
netz, considered in reference to other deposits of the same age, is to 
be found in the north-western English districts of mountain lime- 
stone, in which several workable seams occur ; though in this com- 
parison it must be stated, that the Russian beds contain much more 
coal than the British strata. But even if we admit that, to some 
extent, there is a similarity in the carboniferous rocks of South 
Russia and the Low Countries, in their being both flanked by cre- 
taceous deposits, we must also not omit to recognise a great dis- 
crepancy, through the presence in the one case of overlying strata of 
the age of the Zechstein, and in the other by the total absence of 
that deposit. 
To considerations of theoretical importance concerning the 
changes which the surface of Southern Russia may have undergone, 
and which are ably put forth by M. Le Play, I will not at present 
advert; reserving my views on these points for the concluding 
chapters of the work upon Russia, when all the elements which my 
friends and myself can bring together shall have been laid before our 
readers, to enable them to see the grounds upon which the conclu- 
sions are based. 
For the present, then, I take leave of this volume of M. Le Play, 
which, though it contains some views of positive geology from which 
I differ, must still be regarded as an important addition to the re- 
cords of physical science, and as possessing much more the charac- 
ter of a good monographie description of a given tract in Russia, 
than anything which, from the extensive nature of our researches, 
my friends and myself will ever be enabled to offer. 
Permian Rocks.—On its eastern frontier, far removed from the 
tract to which allusion has been made, the uppermost member of 
the carboniferous limestones of Northern and Central Russia, di- 
stinguished by the presence of multitudes of the foraminifer Fusu- 
lina, is succeeded by the most widely spread of the Russian systems ; 
to which, from its occupying the whole of the ancient kingdom of 
Permia, we have assigned the name of Permian. You have been 
