DE VERNEUIL AND d'aRCHIAC ON RUSSIAN PALEOZOIC FOSSILS. 1 1? 



cal area which they occupy, or, in other words, between their distri 

 bution in space and in time, — relations on which was founded the pro- 

 position enunciated by M. d'Archiac and one of ourselves, namely, 

 " that species which are found in a great number of localities and 

 in very distant countries, are almost always those which have lived 

 during the formation of several successive systems*." 



Of the 392 species which we have observed in Russia, 205, or 

 more than half, are peculiar to that country. Some of these, it is 

 true, differ so little from species found in the deposits of the same 

 age in the west of Europe, that we may look upon them as their 

 representatives ; but still there are such marked differences between 

 the faunas of the two extremities of Europe, that we are bound to 

 admit the important fact, that even at this early period species were 

 not uniformly distributed throughout distant seas, but, on the con- 

 trary, were already grouped into localities, marking in their distri- 

 bution those geographical divisions or groupings into limited areas 

 which were more and more distinctly marked in after-times f. 



Confining our view of the Russian palaeozoic fauna to the species 

 thence obtained by ourselves, we may observe, j^rs^, that they are 

 all marine, with the exception of some shells associated with land 

 plants in the Carboniferous and Permian system ; and secondly^ that 

 there are very few species passing from one system into another, 

 notwithstanding that the rocks very frequently indicate such pass- 

 age. 



If, however, instead of limiting the comparison in this way to the 

 Russian species, we include the general European palaeozoic fauna, 

 we may observe, first, that the number of species common to both 

 faunas (the Russian and general European) is sufficient to satisfy 

 us that the sea then covering Russia was in communication with 

 that covering Western Europe. Seco7idly, that there is at the same 

 time a sufficient number of species confined to each locality to prove 

 that the distribution then was not very different from what is ob- 



* Trans. Geol. Soc. of London, 2ncl ser. vol. vi. p. 335. The observations of 

 geologists in America, as well as our own in Russia, tend to strengthen this po- 

 sition. It may be worth while to mention, as examples, some of the most widely- 

 spread species, as for instance, Favosites gothlandica, F. polymorpha, StromatO' 

 pora concentrica, Terebratula reticularis, T. aspera, T. concentrica, T. elongata, 

 T. sacculus, T. pugnus, T. cuboides, T. Wilsoni, Pentamerus galcatus, Spirifer gla- 

 ber, Orthis crenistria, 0. lunata, O. resupinata, 0. striatula, Lcptccna depressa, 

 Chonetes sarcinulata, Melania rugifera, Bellerophon Urii, Phacops macrophthalma, 

 P. Bowningice, Calymene Blumenbachii, Brontes flabellifer, &c. This rule is not 

 only applicable to the distribution of species vertically through thick deposits, but 

 also to their distribution in existing seas ; for Professor E. Forbes has observed 

 in the iEgcan Sea, that the species which can exist at very different depths be- 

 neath the surface are generally those most widely observed in horizontal exten- 

 sion. (Report of the Thirteenth Meeting of the British Association.) 



t "Whilst in Russia the number of species peculiar to the country amounts to 

 one-half, in North America it is still more considerable in consequence of the 

 greater distance. Of 184 species from the state of New York, described by Mr. 

 J. Hall, about three-fourths are peculiar to the new world ; and in the fine col- 

 lection of American fossils which Mr. LycU has obligingly placed at our disposal, 

 at least five-sixths of the species have appeared to us distinct from those of Eu- 

 rope. 



