88 Professor Ehrenberg on Fossil Itifusoria. 



itself like iron. The red was the thread-like extremities of the 

 Gaillonella. They could not therefore have been heated in the 

 air. The regular horizontal stratification of the polishing slate 

 (probably resulting from a sort of annual, or periodical deposi- 

 tion of tabular masses), is also an argument for Neptunian 

 agency. Moist vapour, arising from neighbouring volcanic ac- 

 tion, without actual fire, may have contributed much to the pu- 

 rifying of the mass. 



These organic relations, in the semi-opal of Bilin, are placed 

 beyond a doubt. The semi-opal of Ghampigny, that from the 

 dolerite of Steinheim near Hanau, and that from the serpentine 

 of Kosemitz in Silesia, exhibit included bodies, bearing a strong 

 resemblance to organic forms. The very distinct, microscopic 

 bodies, occurring enclosed in these minerals, and also adhering 

 externally, like white flour, to the semi-opal of Kosemitz, or 

 filling its internal cavities, may belong to the recent genus Pyxi- 

 dicula. They are quite different from [the little stalactitic co- 

 lumns exhibited by the round eyes in agates. 



It was very natural that I should again examine the chalk- 

 flints which I had so often investigated ; and, on the present oc- 

 casion, I was more successful, from having employed a higher 

 magnifying power. The black, partially transparent flints, pre- 

 sent no distinct traces of microscopic organic remains, but many 

 animal forms are to be seen in the opaque white and yellow flints. 

 The rare, horizontally striped varieties, much resemble the 

 striped semi-opals. All frequently contain spindle-shaped or 

 globular bodies, provided with an opening that can hardly be an 

 optical appearance, and enveloped in a transparent siliceous mass. 

 We sometimes observe in the latter, as in the Gaillonella va- 

 rians of Cassel, radiating stripes proceeding from the pierced 

 centre to the circumference, and also a pretty distinctly marked 

 separate shell. The chalky envelope and white covering of 

 flints does not effervesce with acids ; it is not chalk but silica, 

 which does not result from decomposition, but is like the skin 

 of a lump of dough, that is, it is that layer of siliceous flour 

 (distinct organized beings) which, during the formation of the 

 flint, was only touched, but not fully penetrated by the dis- 

 solving or replacing liquid. It is thus pretty evident, that chalk- 

 flints are formed nearly in the same manner as the semi-opals of 



