184 Observations regarding Fossil Infusoria. 



Jyzed by KJaproth, has shewn, that they also consist almost ex- 

 clusively of the shells of infusory animals of several genera of Ba- 

 cillariae chiefly of species still living, and also of a few siliceous 

 spicula of sea and fresh-water sponges ; but without any uniting 

 basis. Thus the discovery of Kutzing, that the coverings of Ba- 

 cillaria? consist of silica, receives new confirmation. 



Several years ago, the author discovered that the ochre-yel- 

 low slimy substance, which sometimes covers the soil in marshy 

 rivulets and ditches, and seems often to be regarded as a depo- 

 sition of oxide of iron, is a very delicate form of the Bacillariae, 

 which, when heated, becomes red, like the oxide of iron, and is 

 very ferruginous ; but which neither loses its form by ignition, 

 nor by the action of acids, and therefore must possess a siliceous 

 covering, that approaches most nearly the genus Gaillonella. 

 Hence, this form was, during the previous year, figured as the 

 Gaillonella ferruginea in plate 10. of the work on Infusoria, 

 which is about to appear. All the ochre surrounding bog iron- 

 ore exhibits siliceous filiform members, as the residue after 

 the removal of the iron. The above appearances render it ex- 

 tremely probable that the Gaillonella ferruginea performs a 

 very important part in the formation of bog iron-ore, whether 

 it be by the direct addition of the iron contained in itself, or 

 by attracting that belonging to neighbouring foreign substances. 

 The species of fossil infusory animals occurring in the above 

 mentioned substances, are the following i 



1. In the Kieselgulir of Franzensbad: 1. Navicula viridis, 

 as the principal mass ; of various dimensions, the largest being 

 \ w ; 2. Navicula gibba ; 3. Navicula fulva ; 4. Navicula Li- 

 brile ; 5. Navicula striatula ; 6. Navicula viridula. (The two 

 last belong to salt water ; all the others to fresh water). 7. 

 Gomphonema paradoxum ; 8. Gomphonema clavatum ; 9. Gail- 

 lonella various ? all fresh-water animals. None of these can be 

 distinguished from the recent species. 



2. In the peat-bog of Franzensbad ; 1. Navicula granulata, 

 the most abundant, and hitherto an unknown form ; . Navi- 

 cula viridis, rare ; 3. Bacillaria vulgaris ? 4. Gomphonema pa- 

 radoxum ; 5. Coccone'is undulata, all living forms ; the last in 

 the salt water of the East Sea. 



3. In the Bergmehl of Santa Fiora : 1. Synedra capitata, 

 a new species forming the principal mass ; %. Synedra ulna ; 



