8 
Fic. 2.—Foraminifera (recent). 
1. Planorbulira Ungeriana 4. Rotalia Beccarii 
2. Triloculina tricarinata 5. Nonionina turgida 
3. Globigerina bulioides 
Fic. 3.—Foraminifera (fossil). 
\ 
+ s 6 7 
1. Globigerina cretacea (imperfect) | 4. Virgulina punctata 
2. Textularia globulosa 5. Lagena levis 
3. Globigerina bulloides (under | 6. Vaginulina legumen 
side) { 7. Discorbina parisiensis 
The Diatomacez which occur in the English Chalk are referred 
to Fragillaria, I. capucina, F. pinnata; there are also many minute 
bodies called crystalloids and morpholites, by Ehrenberg, which 
have been regarded as belonging to simple Protozoa or to Alge. 
The recent and previous deep sea explorations have shewn that 
the mud forming at the bottom of the Atlantic is not of uniform 
character throughout or due to the same organisms, for in the 
circumpolar Arctic and Antarctic areas a silicious deposit is being 
formed, chiefly derived from the diatomaceous plants and radiolarian 
animals which throng the surface, and from the spicula of the 
sponges which live at the bottom, while in the intermediate zone, 
occupying some 100 degrees of latitude, the composition of the 
deep-sea mud ‘is entirely different trom that of the circumpolar 
regions. 
Thus, in the whole of the ‘‘ intermediate zone,” the silicious 
deposit which is being formed there, as elsewhere, by the accumu- 
lation of sponge-spicula, Radiolaria, and Diatoms, is obscured and 
« 
7 
