NARRATIVE OF THE CRUISE. 
913 
This deposit is one of the purest Globigerina oozes obtained during the cruise, and is 
almost wholly composed of the dead shells of surface organisms. The carbonate of lime 
present is estimated to be made up as follows : — 
Pelagic Foraminifera, ....... G5'00 per cent. 
Pelagic Mollusca, . . . . . . 2 '00 „ 
Coccoliths and Rhabdoliths, ...... 15 '00 „ 
Fragments of Echinids, Ostracodes, Polyzoa, otolitlis, teeth, valves of Lepas , 
fragments of bottom-living Mollusca and bottom-living Foraminifera, 8 - 38 „ 
9038 per cent. 
The bottom-living Foraminifera do not appear to make up more than 1 per cent, of 
this deposit. The great majority of the finest portions are made up of Coccoliths, 
Rhabdoliths, primordial chambers and very young specimens of pelagic Foraminifera. 
On comparing this deposit with one nearer the Equator it is noticed that the majority 
of the shells of pelagic Foraminifera are much smaller and thinner shelled in the former 
than in the latter, the younger specimens are much more numerous, and the predominat- 
ing species are also different. The same remarks hold good for the specimens taken on 
the surface. 
More than two litres of this ooze were dissolved in hydrochloric acid, and in this wav 
a relatively large quantity of the residue was obtained. The magnetic particles were in 
the first place extracted by means of a magnet ; the larger mineral particles and siliceous 
organisms were afterwards separated by decantation. The mineral particles and siliceous 
organisms thus obtained formed but a small portion of the residue, the greater part of 
which consisted of what are denominated “fine washings” (see PI. N, fig. 5). 
These fine washings are deep brown or maroon in colour, greasy, and do not contain 
particles sensible to the touch. The material is but slightly plastic, when dried it 
becomes yellowish brown, forming lumps which break easily and absorb water quickly 
without breaking up; the streak is lustrous. It reddens with heat, and melts easily 
before the blow-pipe into shining beads, which are black and magnetic. These globules 
examined by the microscope appear as a brownish glass, filled with gas cavities. Some 
of these characters apply to what is usually called a clay, but some of the properties, 
especially the pyrognostic properties, show that it is not a pure clay, but a mixture of 
different materials. An examination of the wet preparations of these fine washings with a 
power of 450 diameters shows that they are composed of an amorphous matter, fragments 
of minerals and rocks, the remains of siliceous organisms, and of colouring substances. 
The amorphous matter, which may be considered as properly the argillaceous matter, 
presents characters essentially vague. It appears as a colloid substance without definite 
contours, generally colourless, perfectly isotropic, and forms a mass which agglutinates 
and connects the other particles of the washings. As these physical characters are 
