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 Menilmontant 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 Bacillariz, and indeed to eight different 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 very 
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 very difficult to 
be observed in the living ones, and have hitherto been overlooked 
by me. I first discovered the apertures of the Gaillonellz 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 Vavicula 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 already often pointed 
out, are deserving of remark: 1. Many Navicule and other Bacillariz have 
quite a distinct, powerful, active, crawling motion, by which they move and 
push 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, 
