208 THE FOREST LANDS OP NORTHERN RUSSIA. 



equal manner over the surface of the globe, whilst from 

 the miocene period there exists in this respect a well- 

 marked inequality which has become still more pronounced 

 in the present day. A comparative study of the marine 

 fauna collected at Bear Island leads to similar results. 



' The Productus giganteus, P. striatus, P. punctatus, and 

 P. hemispJiericus, which we know to have existed in the 

 mountain limestone of this island, have been found almost 

 everywhere in the mountain limestone, and possessed an 

 extension equivalent to that of the Knorria imbricata, of 

 the Lepidodendron Velthrimianum, and of the Catamites 

 radiatus. Further, two moluscs of the mountain limestone 

 of Spitzbergen, Spirifer Keilhauii and Productus costatus, 

 have been found also in India; and another species, the 

 Productus Humboltii. in South America, so that the Polar 

 species stretched then to the tropics. The presence at 

 this epoch of a climate not only equal, but also warm, is 

 further proved by the banks of coral which were formed 

 at Spitzbergen, and also by the great dimensions of the 

 arborescent cryptograms, and by the ferns with large 

 fronds preserved in Bear Island.' Thus far Dr Heer. 



Count Saporta remarks on this : ' A picture so vivid, 

 and so complete, beyond the interest which attaches to 

 itself, is well fitted to suggest some reflections. M. Heer 

 does not admit, and that with reason, that the entire earth 

 has ever been submerged during the epoch of maritime 

 invasion represented by the mountain limestone. He 

 perceives the necessity there is for the supposition of one 

 or more continents having existed, serving as an asylum 

 for the plants driven back from the invaded portions, 

 which then reappeared at the time of the culm, and 

 of the coal, properly so called, the one class under the 

 same form as before, the others represented by allied 

 forms, though distinct. But M. Heer expresses astonish- 

 ment that certain types were lost after the culm without 

 again reappearing, although they had traversed without 

 any modification the long period which just elapsed since 

 the extreme base of the inferior carboniferous strata/ 



