REVIEW OF THE PERMIAN FOSSILS. 
211 
the upper chalk, whilst he describes 134 in the lower member of the formation 
( craie chlorite'e). 
If future discoveries and a more perfect acquaintance with the zoology of these 
epochs, should oppose no evidence to conflict with that which is now accumulated, 
some persons might be led to perceive in this grand and intermittent phenomenon, 
the recurrence of a general law. Whilst, however, our present acquaintance with 
their respective faunas would certainly lead us to conclude, that the Permian and 
Cretaceous systems have each preceded an almost entire renovation of animal life, 
it is right to state, that judging from many of their generic forms, the upper secon- 
dary rocks seem to have prepared the way for the sequence of the tertiary strata. 
In short, some geologists, including ourselves, who have contended for this view, 
aie still disposed to think, that with increased observation, a zoological passage 
may be discovered between the upper chalk and the lower tertiary deposits. 
But after all, we are far from wishing to draw Avide conclusions from limited 
and insufficient data ; and we are too well aware of the recency of the discovery 
of multitudes of species in the older Palaeozoic rocks, not to be alive to the 
necessity of much caution in deducing- general zoological inferences. We have 
still, however, great reliance on the fact, that few strata have been longer or more 
assiduously examined, than the Zechstein and Kupfer-schiefer of the Germans 
and the Magnesian Limestone of the English ; and, as the activity of modern col- 
lectors has added little to our stock of knowledge of the animal remains of these 
rocks, we have a fair right to reason upon the general character of their fauna. 
Yet more haA r e we autliox’ity to take this view, when by traversing the vast basin 
of Russia, occupied by synchronous strata, we find the same group of fossils and 
the same species extending from the mouth of the Petchora and the country of the 
Samoyedes upon the Northern Ocean, to the south of Orenburg, or over upwards 
of 1 8 degrees of latitude 1 ! 
1 Whilst we write we have received intelligence from our friend and colleague, Count Keyserling, that 
in an expedition during the last summer with M. Krusenstern, to determine the geographical outlines, 
geological structure, and natural productions of the region around the embouchure of the Petchora, he 
has there traced the Permian strata occupying the plateaux on its left bank ; the depressions being occu- 
pied by Jurassic and post-pleiocene deposits. He has further discovered an undescribed low chain of 
mountains called the Timans, forty to fifty versts wide, which, trending from the sources of the Vitchegda 
to the north-north- west, forms the eastern limit of the Permian deposits, and is separated from the Ural 
by the very broad intervening trough of the Petchora. In this ridge and trough, as in the North Ural, the 
Permian rocks do not exist ; the only sedimentary strata being the Lower Palmozoic, which arc associated 
