476 
Proceedings of the Royal Society 
see how the sorting which takes place in the transport of the ashes 
of a volcano has its analogy in what we find in the deep sea deposits. 
In the First Part of this communication we shall give the miner- 
alogical description of the fragmentary products of Krakatoa, and 
consider generally the observations relative to these ashes. We 
shall also give the diagnostic characters of this volcanic dust, and of 
all similar particles which we find in deep sea deposits. In the 
Second Part, we will treat of the cosmic matters found in the 
abysmal regions of the ocean, to which Mr Murray was the first to 
draw attention, and discuss their origin and distribution. 
First Part. 
It is unnecessary to refer to the abundance of floating pumice, to 
its various degrees of alteration, to its conveyance by means of 
rivers, waves, and currents, and to its universal presence in deep sea 
deposits, which have been pointed out in some detail in Mr Murray’s 
paper above referred to ; but we will briefly recapitulate the char- 
acters of these volcanic matters, in accordance with the examination 
we have made of a large number of soundings and dredgings. We 
need not describe in detail the special characters of the lapilli which 
have been brought up in the dredge and sounding-rod from great 
depths. These fragments of more or less scoriaceous rocks belong 
to the same lithological varieties as those derived from terrestrial 
volcanoes. They consist of fragments of trachyte of various dimen- 
sions, of basalt, and, above all, of augite-andesite ; the most remark- 
able, beyond all question, being lapilli of sideromelan, which are 
often entirely transformed into palagonite, and pass into the clay 
which is found so widely distributed, especially in the Pacific. 
We do not propose here to take up in detail the wide distribution 
of the materials ejected from Krakatoa; we are engaged in collect- 
ing these, and will place the observations on maps along with 
those of Mr Buchan on the upper currents of the atmosphere, which 
will be published in the ‘‘Challenger” Beports. 
Before, however, passing to the description of the ashes themselves 
we will briefly refer to some points touched upon by Mr Murray in 
his paper. It is there pointed out that, in regions far removed from 
coasts, rounded fragments of pumice were collected on the surface 
of the sea by means of the tow-net, and that, at certain points on 
the bottom of the ocean, the greater part of the deposit is composed 
