THE DEPTH AND MARINE DEPOSITS OF THE PACIFIC OCEAN. 29 
two other stations where the deposit is a Red Clay. The nodules are of low 
specific gravity, with no shining lustre, and are rather incoherent, being 
always mixed with a large proportion of foreign elements. 
The first stage towards the formation of nodules is represented by cakes 
of palagonite and other decomposed minerals (chloritic minerals and decom- 
posed felspar, besides palagonite formed by decomposed glass), in which the 
mineral particles are coated with a thin layer of the oxides ; the whole cake 
may also be coated with the oxides. The more perfect nodules are not 
formed of solid oxides, but round a core of palagonite comes a layer of 
oxides, then another layer of palagonite, and the latter is again covered 
with oxides, and so on. 
The most: interesting point about this station is that it contains remark- 
able examples of deposition of manganese-iron oxides round very different 
centres of accretion: we have here some curiously shaped pseudo-nodules 
which are undoubtedly siliceous sponges impregnated with manganese and won 
oxides. The entire sponge is not always wholly preserved, but the siliceous 
skeleton can always be detected, unaltered, in the midst of the oxides in 
which it is embedded. : 
Organisms, sometimes of large size (Hydroids), are specially abundant, 
and can be seen attached in their original position on the surface of nearly 
all the specimens. They are often distributed on the whole of the surface 
of the nodule, so that the latter was either not deeply buried in the mud, or 
had its position shifted. 
The lack of metallic lustre alluded to is very likely due to the large pro- 
portion of palagonite and other products of decomposition, taking part in the 
formation of the nodules. 
It may be added that it was possible to observe on certain grains of 
palagonite the gradual transformation of brown volcanic glass into that 
mineral, but such instances are of rare occurrence. It was also found, in 
studying this material, that certain crystalline minerals, possibly felspar, 
form products of decomposition very similar to that of volcanic glass. 
Station 4658, 14th November, 1904. Lat. 8° 29.5'S.; long. 85° 35.6’ W. ; 
depth, 2370 fathoms. 
The nodules from this station (see Pl. 1, figs. 7, 2) are as remarkable for 
their large size as for their constant shape, which is on a definite pattern. 
These nodules have each two surfaces, which are, roughly speaking, re- 
