UPON FOSSIL INFUSORIA. 61 



lose its form either by a red heat or upon being- treated with acids, 

 and, consequently, possesses siliceous armour most approximating to 

 that of the genus Gaillonella. I therefore figured it last year as 

 Gaillonella ferruginea, in plate ten of my Infusorien Codex, which 

 will now soon appear. The above circumstances make it probable 

 that G. ferruginea played an important part in the formation of bog 

 iron, either by the direct amount of its own iron or by the attrac- 

 tion of all in its vicinity. 



The following are the fossil species of infusoria which I have de- 

 tected in the above-named substances : — I. In the siliceous concrete 

 (kieselguhr) of Franzensbad: \. Navicula viridis of very different 

 sizes, the largest i", forming the major part of the mass ; 2. N, gib- 

 ba ; 3. N.fulva ; 4. N. Librile ; 5. N. slriatula ; 6. N. viridula ; 

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

 fresh water) ; 7- Gomphonema paradoxum ; 8. G. claratum ; 9. 

 Gaillonella varians ? all fresh- water animals — none to be distin- 

 guished from the living species. II. In the peat of Franzensbad : 

 1. Navicula granulata is the most numerous, and was hitherto un- 

 known ; 2. N. viridis, rare ; 3. Bacillaria vulgaris ? 4. Gomphone- 

 ma paradoxum ; 5. Cocconeis undulala ; all living forms — the last 

 found in the salt water of the Baltic. III. In the brugmehl of 

 Santa Flora : 1. Synedra capilata, forming the chief mass — an hi- 

 therto unknown form ; 2. S. ulna ; 3. N. Librile ; 4. N. gibba ; 5. 

 N. viridis; 6. N. capilata; 7- N. zebra; 8. N. phoeniceutron ; 9. N. 

 inequalis (all 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. 

 accuminatuin (all still found in fresh water) ; 16. Cocconema cym- 

 biforma (a still existing fresh-water animal) ; 17- Cocconeis undu- 

 lala (still found in salt water) ; 18. Gaillonella Italica, n. s. ; 19. 

 the siliceous spicula of a spongia or spongilla. IV. Klaproth's sili- 

 ceous concrete (kieselguhr) from the Isle of France, exhibited, 1. 

 Bacillaria vulgaris? constituting the chief mass; is still found 

 everywhere in salt water ; 2. B. major (an unknown species) ; 3. 

 Navicula gibba (still living, both in fresh and salt water) ; 4. N. 

 alia (sp, undetermined) ; 5. N. bifrons : all these species are not 

 so well preserved as those in the former stones, 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 greater 

 number arc so well preserved that they may be closely inspected. 

 Thus, for instance, it is not only possible (o count the number of 



