PROF. EHRENBERG ON FOSSIL INFUSORIA. 405 



1 . Podosphenia nana, new species, as chief mass ; 2. Gaillonella 

 distans, new species ; 3. Navicula Scalprum ? ; 4. Bacillaria 

 vulgaris ? probably all sea animals. 



VI. In the leaf-tripoli of the shops at Berlin, probably received through 

 Dresden or from the Harz, were found three precisely corresponding 

 species : 



1 . Gaillonella distans, as chief mass ; 2. Podosphenia nana, new 

 species; 2. Bacillaria vulgaris?. 



VII. In the Klebschiefer from Menilraontant I in two instances 

 found fragments of Gaillonella distans, but am doubtful whether they 

 may not have been derived from the Schiefer of Bilin. 



It deserves particular notice, that by far the greater number of these 

 twenty-eight fossil species of infusoria, which all belong to the family 

 of the Bacillarise, and indeed to eight diiferent genera now existing, — 

 namely the genera Navicula, Cocconeis, Synedra, Gomphonema, Cocco- 

 nema, Podosphenia, Bacillaria, Gaillonella, — that of these twenty-eight 

 species, fourteen were undistinguishable from existing freshwater infu- 

 soria, and five species from existing marine animals. The other nine 

 species, therefore not quite one third, are either as yet undiscovered 

 but existing forms, or extinct ones. It however appears to me more 

 probable, from a comparison of my extended observations of these na- 

 tural bodies, and bearing in mind the circumstance that no extinct 

 species appear exclusively in the above-mentioned fossil relations, that 

 the new fossil species, among which is no new genus, are not extinct, 

 but still existing ones which have not yet been discovered. 



The great mass of the specimens of these animal forms is in verj'' 

 good preservation : many of them are so beautifully preserved, that 

 I have even been able to determine from them the characters of the 

 living species more precisely ; for a direct comparison of the latter showed 

 that certain apparent characteristical distinctions are veiy difficult to 

 be observed in the living ones, and have hitherto been overlooked 

 by me. I first discovered the apertures of the Gaillonellae in the Po- 

 lirschiefer, and I now perceive them in all the species of the genus : I 

 have never before seen the six apertures of Navicula viridis so beau- 

 tifully*. 



The great sharpness and clearness of all the outlines of all these 

 siliceous shields plainly appears to have been produced by an extra- 



• As botanists have often regarded these forms as plants, the following 

 reasons why they are considered as animals, which I have akeady often pointed 

 out, are deserving of remark: ]. Many Naviculse and other Bacillariae have 

 quite a distinct, powerful, active, crawling motion, by which they move and 

 j)ush aside other bodies much greater than themselves. 2. The projection of 

 an organ similar to the foot of a snail, and whose action assists in crawling, 



