162 -Ehrenberg on Fossil Infusoria* [Jan, 



cious opal, and found that a mass similar to Steinmark (lithomarge) 

 always immediately surrounds the nodules. Tiiis Steinmark of Kas- 

 chau exhibits however, under the microscope, a great resemblance to 

 the Gaillonella distans, as it appears in the Saugscliiefer of Bilin. I 

 have, from the remarkable character of the primary formation, repeat- 

 edly examined and compared these and vsimilar phaenomena, and pre- 

 fer to declare them openly than to keep them secret. I shall how- 

 ever continue my observations with close examination, and publish 

 the results if they lead to any discovery, when they are sufficiently ma- 

 tured. 



The more probable appears the proverb, partly old and partly new, 

 Omnis calx e vermibus, Omnis silex e vermibus, Omne ferrum e vermis 

 bus, the more necessary it is, by continual and close examination, which 

 cannot be the work of a day, to separate facts from opinions^ and not 

 to envelope them in mystery, but by careful observation to confine 

 them within the probable and attainable limits which nature has as- 

 signed. We may regard as hitherto ascertained facts that 



1. Bergmehl > 



V Newest formation. 



2. Kieselguhr3 



3. Polirschiefer , , "J 



4. Saugschiefer > Tertiary formations 



5. The semi-opal of the Polirschiefer) 



consist entirely or partly of the shells of shield-infusoria. 

 The following species of stone are very -probably of the same nature t 



6. The semi-opal of the Dolerit J 



7. The (precious) opal of the porphyry [ ^'^^1^^^ ^'''"^^'^ 



8. The flint of the chalk 3 



9. The Gelberde (yellow earth)]? 



S- Newest formation. 



10. The Easeneisenstein 3 



11. Certain kinds of Steinmark*. — Scientijic Memoirs, vol. i. 

 part iii. 



* The examination of a boulder from the Mark (Brandenburg) which has been regard- 

 ed as Schwimmstein (compare Klo den, Gcognost. Mem. 1834, p. 30.) has lately proved 

 to me that its chief mass consists of just the same detached siliceous spindles of sponges 

 and of the minute globules (infusoria Fijxiclicula 1) which the flint boulders of the Mark 

 inclose in great numbers. These bodies also lie in the meally covering of the flint. 

 This Schwimmstein therefore bears the same relation to the flint sis the Polirschiefer to 

 tlxe semi-opalj and it belongs to the chalk. 



