REPOET ON THE DEEP-SEA DEPOSITS. 
317 
particles present the same characters as in the preceding figures, associated with crystals 
or splinters of felspar, plagioclase, augite, and magnetite. Among the particles may be 
observed bipyramidal crystals of quartz, which may have come from the disintegration 
of a liparitic rock. In PI. XXYII. fig. 5 the aspect of the minutest particles of 
the fine washings of a Eadiolarian Ooze is represented, from Station 225, 4475 fathoms. 
West Pacific. In addition to the debris of organisms, there may be observed little 
fragments of volcanic minerals, or splinters of colourless glass with a porous appearance. 
PL XXVI. fig. 1 represents the mineral particles from the residue of a Globigerina Ooze, 
in the South Pacific, Station 300, 1375 fathoms; these are observed to have the same 
characters as in the case of the Eed Clays, consisting of vitreous particles associated with 
splinters of felspar, plagioclase, magnetite, augite, and minute grains of manganese 
peroxide. 
If now we pass to the mineral particles in terrigenous deposits, we may still in some 
instances recognise an abundance of vitreous particles, as, for instance, in the deposit 
called a Blue Mud, in the South Pacific, Station 303, 1325 fathoms, represented in 
PL XXVI. fig. 4. Here the mineral particles are almost exclusively formed of splinters 
of a brownish glass, more or loss vesicular, the pores being generally rounded, but 
associated with these are colourless particles with a filamentous structure, which are 
probably derived from acid glasses. The predominance of vitreous particles and volcanic 
minerals in a Blue Mud is also represented in PL XL fig. 2, showing the mineral particles 
from Station 237, 1875 fathoms, North Pacific. Here there are seen besides the 
fragments of plagioclase, sanidine, augite, hornblende, and magnetic grains, many 
splinters of vitreous matter which are present under three different aspects — some 
transparent, slightly violet, or almost colourless, fibrous with cylindrical pores, as may 
be seen in the lower part of the figure and near the upper left hand side ; other 
vitreous splinters are deep brown, almost opaque, with large, more or less circular, pores ; 
and again these vitreous particles are transformed into a reddish brown resinoid 
substance, resembhng palagonite, as may be seen on the right hand side of the figure. 
In PL XXVII. fig. 1, which represents the mineral particles in a Volcanic Mud, off the 
Sandwich Islands in the North Pacific, Station 262, 2875 fathoms, we have a most 
typical example of these vitreous fragments. The Whole field of the microscope is 
occupied by vitreous particles, slightly brownish in colour, with relatively few pores, 
but presenting the characteristic fracture and outlines of these glassy fragments. 
All the figures to which we have referred represent these particles in an isolated 
condition in the deposit. In the compact tufas which were dredged from the bottom of 
the sea they present a slightly different aspect. 
In the Tables of Chapter II. vitreous particles are recorded in 45 specimens of Eed 
Clay, 6 of Eadiolarian Ooze, 4 of Diatom Ooze, 63 of Globigerina Ooze, 6 of Pteropod 
Ooze, 20 of Blue Mud, 3 of Eed Mud, 10 of Green Mud, 20 of Volcanic Mud, 3 of 
