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encompassing bog-iron ore exhibits the same siliceous Aliments 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 I 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 ; 8, 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 was hitherto unknown ; 2, Nav. viridis , rare ; 8, Baccillaria vulgaris ? 
4, Gomphonema paradoxum ; 5, Cocconeis undulata . All living animals, the 
last found in the salt-water of the Baltic. 
3. In the mountain flour (Bergmehl) 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 , all still living in fresh water ; 10, N viridula, 
found still in salt-water; 11, N. granulata; 12, N. follis, 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, Cocconeis 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, 
