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encompassing bog-iron ore exhibits the same siliceous filiments as a deposit after 

 the extraction of the iron. The above circumstances make it probable that the G. 

 ferruginea played an important part in the formation of bog-iron, either by the direct 

 amount of its own iron, or by the attraction of all in its vicinity. 



The following are the fossil species of Infusoria which T have detected in the 

 above-named substances : — 



1. In the siliceous concrete (Kieselguhr) of Franzensbad: — 1, Navicula 

 viridis of very different sizes, the largest l-9th'" forming the major part of the mass ; 

 2, N. gibba ; 3, N. fulva ; 4, N. Librile ; 5, N. striatula ; 6, N. viridula — 

 (the last two are salt-water animals, all the first are inhabitants of fresh water) ; 

 7, Gomphonema paradoxum ; 8, G. clavatum ; 9, Gaillonella varians ? All 

 fresh-water animals, and none to be distinguished from the living species. 



2. In the peat of Franzensbad: — 1, Navicula granulata is the most nume- 

 rous, and wa*s hitherto unknown ; 2, Nav. viridis, rare ; 3, Baccillaria vulgaris ? 

 4, Gomphonema paradoxum ; 5, Coccone'is undulata. All living animals, the 

 last found in the salt-water of the Baltic. 



3. In the mountain flour (JBergmehl) of Santa Fiora : — 1, Synedra capitata, 

 forming the chief mass, an hitherto unknown form ; 2, S. ulna ; 3, Navicula 

 Librile; 4, N. gibba; 5, N. viridis; 6, N. capitata; 7, N. zebra; 8, N. 

 phcenicenteron ; 9, N. inequalis, alt still living in fresh water ; 10, N. viridula, 

 found still in salt-water ; 11, N. granulata; 12, N. Jbllis, unknown species. 

 13, Gomphonema clavatum ; 14, G. paradoxum ; 15, G. acuminatum, all still 

 found in fresh water ; 16, Cocconema cymbiforme, a still existing fresh-water 

 animal; 17, Coccone'is undulata, still found in salt water; 18, Gaillonella ita- 

 lica, n. sp. ; 19, the siliceous spicula of a Spongia or Spongilla. 



4. Klaproth's siliceous concrete (Kieselguhr) from the Isle of France 

 exhibited : — 1, Bacillaria vulgaris ? constituting the chief mass, and is still found 

 every where in salt water ; 2, B. major, an unknown species ; 3, Navic. 

 gibba, still living both in fresh and salt water ; 4, Navic. alia sp. undeter- 

 mined ; 5, N. bifrous. All these animals are not so well preserved as those in 

 the former rocks, and appear, with the exception of the latter, to be salt-water 

 animals. 



The majority of these fossil Infusoria are still found living near Berlin, and in 

 the waters of the Baltic near Wismar. The majority are so well preserved that 

 they may be closely inspected. Thus, for instance, it is not only possible to count 

 the number of the ribs, but also the six apertures of the case of Navicula viri- 

 dis, the four apertures of Gaillonella, the two apertures of Gomphonema, &c. 

 The rock of the Isle of France only, appears to contain a preponderance of salt- 

 water animals. The few hitherto unknown forms may be considered very appropri- 

 ately as still existing, although yet undiscovered animals. What is most striking is 

 the preponderance of individual species which thereby characterize the different rocks, 



