PBOGEESS OF MICROSCOPICAL SCIENCE. 
313 
several soundings in the Soutli Pacific, manganese in tlie forms of 
grains and nodular concretions is very abundant. As a rule, however, 
this substance occurs rather sparingly in Glohigerina-ooze. In some 
instances we get little nodules of these bottoms, the shells as it were 
being run together by a silicious cement. Many small pieces of 
cherty-like mineral also occur, which are angular and soft, and do not 
look as if they had been transported. Manganese nodules occurring in 
the Glohigerina-ooze have often a nucleus of a yellow and green colour, 
in which Globigerina-shells can be seen ; but their carbonate of lime 
has been entirely removed, and replaced by a silicate. There are 
reasons for thinking that these indications of flint (?) occur only in 
those samples where the silicious shells of Eadiolaria, Diatoms, &c., 
are wanting, and do not occur where these organisms are present. 
A re-examination of all the bottoms must be made before this state- 
ment can be definitely affirmed. Casts of Foraminifera occur very 
sparingly in Glohigerina-ooze ; in the purest samples not at all. In 
those with an admixture of clayey matter we have frequently one or 
two partial casts of a very rough character. In two soundings, Nos. 
211 and 301, in the Pacific, we found the Foraminifera not only 
filled, but also coated with a red substance, so that we had both an 
internal and an external cast, the two being connected by little 
rods representing the foramina of the shell. In these soundings 
there was much clayey matter and disintegrating pumice and scoria. 
In a few soundings in the Pacific, as No. 304, we have had a 
Glohigerina-ooze on the surface of the bottom, and a foot beneath a 
nearly pure red or brown clay. Again, as in Nos. 268 and 307, we 
have the reverse arrangement, a clay occupying the surface, and the 
deeper layers having many Glohigerince. In all these cases the sur- 
face layer has been normal with the other soundings in the same 
region as to depth. In the first case we might bring in elevation to 
account for the Gloherina-ooze overlying the red clay, or we might 
suppose that chemical changes are going on in the deeper layers which 
remove the carbonate of lime. In the second case we may account 
for a red clay overlying a deposit with many Gloherince in it by sup- 
posing a depression of the bottom after the latter had been laid down ; 
or we may believe that agencies are now removing carbonate of lime 
from the surface layer, and that these were not active in some past 
time. 
This deposit occurs, in one sounding, in the Pacific at a depth of 
2925 fathoms in mid-ocean. In the eastern part of the Atlantic it 
occurs also at great depths. 
Professor NordensMold's Microscopic Examination of Volcanic 
Dust. — Professor Nordenskiold, in a paper which has been translated 
by our contemporary, the ' Geological Magazine,' gives the following 
account of the dust which was brought down by a snow-storm on the 
hot-beds of one of the Eoyal Swedish residences. He states that 
" some of the dust was collected and examined under the microscope, 
and found to consist for the greater part of small, translucent (or 
transparent), angular, uncoloured, glass-like particles, which formed 
elongated filaments, bent sabre-fashion, or sharp-cornered flat bodies. 
