NOTES AND MEMORANDA. 391 
prepared of the details of this process, and either Mr. Murray 
or I will shortly describe it more in full... . 
“Our soundings in the Atlantic certainly gave us the 
impression that the siliceous bodies, including the spicules 
of Sponges, the spicules and tests of Radiolarians, and the 
Frustules of Diatoms which occur in appreciable propor- 
tions in Globigerina ooze diminish in number, and that 
the more delicate of them disappear, in the transition from 
the calcareous ooze to the ‘red clay ;’ and it is only by this 
light of later observations that we are now aware that this 
is by no means necessarily the case. On the 23rd of March, 
1875, in the Pacific, in lat. 11° 24’ N., long. 148° 16’ E., 
between the Carolines and the Ladrones, we sounded in 4574 
fathoms. ‘The bottom was what might naturally have been 
marked on the chart ‘red clay ; it was a fine deposit, reddish 
brown in colour, and it contained scarcely a trace of lime. 
It was different, however, from the ordinary ‘red clay’— 
more gritty—and the lower part of the contents of the sound- 
ing-tube seemed to have been compacted into a somewhat 
coherent cake, as if already a stage towards hardening into 
stone. When placed under the microscope it was found to 
contain so large a proportion of the tests of Radiolarians, 
that Murray proposes for it the name ‘ Radiolarian ooze.’ 
This observation led to the reconsideration of the deposits 
from the deepest soundings, and Murray thinks that he has 
every reason to believe (and in this I entirely agree with 
him) that, shortly after the ‘red clay’ has assumed its most 
characteristic form, by the removal of the calcareous matter 
of the shells of the Foraminifera, at a depth of say 3000 
fathoms, the deposit begins gradually to alter again by the 
increasing proportion of the tests of Radiolarians, until, at 
such extreme depths as that of the sounding of the 23rd of 
March, it has once more assumed the character of an almost 
purely organic formation, the shells of which it is mainly com- 
posed, being, however, in this case, siliceous, while in the 
former they were calcareous. The ‘ Radiolarian ooze,’ 
although consisting chiefly of the tests of Radiolarians, con- 
tains, even in its present condition, a very considerable pro- 
portion of red clay. I believe that the explanation of this 
change, which was suggested by Murray, and was indeed 
almost a necessary sequence to his investigations, is the true 
one. We have every reason to believe, from a series of 
observations, as yet very incomplete, which have been made 
with the tow-net at different depths, that Radiolarians exist 
at all depths in the water of the ocean, while Foraminifera 
are confined to a comparatively superficial belt. At the sur- 
