PROF. EHRENBERG ON FOSSIL INFUSORIA. 413 
Explanation of the Figures ( Plate V). 
Fig. 1. Navicula ( Surirella) viridis, 4 lin. magnitude, in the Kiesel- 
guhr of Franzensbad: a, seen from the side surface, where 
the mouths of the three apertures are apparent ; 6, the same 
individual from the dorsal or ventral side, in which are seen 
all the six apertures. The stripes are internal raised bands, 
between which were situated the ovaries of. the living ani- 
mal. 
Fig. 2. Navicula (Surirella) granulata, from the peat-bog of Franz- 
ensbad ; a, side view; 6, the under surface. 
Fig. 3. 1. Synedra capitata, the chief form of the Kieselguhr of San 
Fiore; a, side surface; 6, ventralsurface. 2. Naviculaine- 
qualis, side view. 
Fig. 4. Bacillaria.vulgaris? chief form of the Kieselguhr of the Isle 
of France. 
Fig. 5. Gaillonella distans, 54, to ~§z lin. thick: chief form of the 
Polirschiefer of Bilin (the leaf-tripoli); a, 6, c, seen from the 
side; d, e, cross surfaces ; f, apertures. 
Fig. 6. Gaillonella ferruginea, +3155 lin. thick ; the animalcule of the 
iron-ochre ; a, with the same magnifying power ; 6, two thou- 
sand times magnified. Lyngbye has regarded this animal- 
cule as the base of his Oscillatoria ochracea. Oscillatoriz 
are sometimes found parasitically within it; they belong 
however to many different genera, and Agardh has there- 
fore rightly regarded them as not distinct species. 
All the other figures are magnified 290 or nearly 300 times. 
QE 
