1838.] 



Prof. Ehrenherg on Fossil hifusoria. 



151 



amined first the common or leaf tripoli, and found at once that this 

 also consisted entirely of the shells of infusoria. All the others were 

 of a different inorganic nature. A comparison of this tripoli of the 

 shops (which, as I was informed, comes from the Harz and Dresden) 

 with the scientifically arranged species of tripoli in the Royal Mine- 

 ralogical Museum, showed that this so-called leaf tripoli is evidently 

 the same stone which was received by Werner as a new species in mi- 

 neralogy under the name of Polirschiefcr (polishing slate), which it 

 has ever since retained. The specimens at hand from the Kritschel- 

 berg, near Bilin, exhibited so perfect a similarity, as well outwardly 

 as in the forms of the infusoria of which it consisted, that it is evident 

 that the leaf-tripoli sold at Berlin comes from Biliu in Bohemia, 

 through Dresden. A similar stone to this is the Polirschiefcr found at 

 Planitz near Zwickau, if indeed the locality of the specimen examin- 

 ed by me be correct. But the Klebschiefer from Montmartre, which 

 Klaproth has analysed, exhibited only doubtful traces of infusoria 

 shields. The appearance of the fossil infusoria in the form of the 

 Polirschiefcr of Bilin is plainly of great importance to our further 

 researches into geognostical relations. In the same slate are found 

 the impressions of an extinct fish, the Leucucus papyrace us of Bronn 

 (according to Agassiz), and several impressions of plants, probably 

 belonging to the tertiary formation. 



I had been inclined, even before these researches, to assign a great 

 influence in the origin of the Rascneisen (bog-iron-ore) to an infuso- 

 rium discovered by me in 1834, and of which I have, in x^pril 1835, 

 given an engraving in Plate X. of my Codex of Infusoria, under the 

 name of Gaillonella ferruginea, which is perhaps the same as the 

 Hygrocrocis ochracea of botanists. The minuteness of these cor- 

 puscles deterred me how'ever from publishing this important circum- 

 stance ; but since the discovery of so many and various shield-infusoria 

 as stone masses, and since I have found that even the animalculaa 

 which almost entirely form the Polirschiefcr of Bilin are also a species 

 of the genus Gaillonella, I no longer hesitate to add this observation 

 to the rest. That the formation of the Raseneisen, or of the Wiesenerz 

 (meadow-earth), as a continual phcenomenon excites great attention, 

 and has given rise to many but not sufficiently explanatory theories, 

 is well known. I have every spring observed in the marshes, par- 

 ticularly in the truf districts about Berlin, large quantities of a sub- 

 stance of a very deep ochre yellow, sometimes passing into fiesh red, 

 often covering to a great extent the bottom of the ditches from one to 



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