216 
REVIEW OF THE PERMIAN FOSSILS. 
Permian species of that country descend into the paheozoic rocks. These results 
prove, that there necessarily exists a relation between the greater or less duration 
of the existence of species and their propagation or extension to distant parts, and 
it confirms, in a remarkable manner, that law previously announced by one of us 1 , 
viz. “ that the species which are found in a great number of localities, in very distant 
countries, are almost always those ivhich have lived during the formation of several 
different systems.” 
Let us now take a rapid view of the species found in Russia, in order to com- 
pare them, in each class, with those of other parts of Europe, and thus to bring 
out in strong relief the contemporaneity of the deposit in distant countries. 
By the study of ichthyolites Palaeontology seemed to teach us, as we have before 
said, that in proportion to their elevation in the animal kingdom, fossils are most 
characteristic of given deposits. But much caution is required before we can reason 
from this doctrine inversely, and infer that the lower the order of animal the more 
uncertain criterion is it of the age of the stratum. From the existence of some species 
of corals, both in Silurian and Devonian rocks of great thickness, it is ascertained, 
that under certain conditions these creatures lived on through very long periods. But 
can we apply this view to the Permian rocks ? Are Polypifers of the pre-existing 
Carboniferous age found in them, and to what extent ? Had our own imperfect know- 
ledge been appealed to, we should have said with our precursors, that several forms 
of this low class of beings were common to the two systems. The philosophic 
researches, however, of Mr. Lonsdale have convinced this great authority on such 
a subject 2 , that when examined under a lens of high power, nearly all the Permian 
corals are seen to be distinct in species from those of the Carboniferous sera. 
Concerning the Brachiopods we may venture to express our own opinion. Of 
twenty species eight are peculiar to Russia, and twelve are already known 
elsewhere. These twelve species are thus distributed : two, viz. Terebratula pec- 
tinifera and T. plica, belong exclusively to the Zechstein of Western Europe ; a 
third, Spirifer undulatus, is doubtful; three, viz. S. cristatus, Terebratula elongata 
and Lingula Mytiloides, are common to the Zechstein and the older formations ; 
one, the Terebratula Schlotheimi, occurs in carboniferous rocks in W estern Europe, 
and in the Permian strata of Russia : and lastly, five others, terebratula Royssii, 
' De Verneuil and D’Archiac, Trans. Geol. Soc. Lond. 2nd series, vol. vi. p. 335. 
2 See Mr. Lonsdale’s Description of the Corals of the Silurian and Devonian rocks in Murchison’s ‘ Silu- 
rian System ;’ also in the Geol. Trans, vol. v. p. 734 ; vol. vi. p. 227 et seq. See also his Description of 
the Russian Corals in an Appendix. 
