280 Proceedings of the Royal Society of Edinburgh. [Sess. 
segregated in some small flint nodules. A 3 certainly contains more 
terrigenous material than the others, but as the whole rock is permeated 
with silica, and it is necessary to reduce it to powder before an analysis 
can be made, it is impossible to estimate the quantity, for particles of 
spicules and silicified calcareous organisms become included in the finer 
portion when levigation is attempted. But microscopical investigation 
of the final residue after treatment with potash shows that organic 
matter is present, the lath-shaped particles occurring plentifully. 
The next boulder I deal with is B 4. The total residue of this specimen 
was 5 04 per cent. ; from this ’52 per cent, of coarse material was separated 
by levigation. There were few spicules in the residue ; such as occurred 
were chiefly fragments of Hexactinellid mesh of robust type. There were, 
however, a large number of Foraminifera, chiefly arenaceous forms, with a 
few Radiolarians (see list), and mineral grains constituted the remainder. 
The size of these was large when compared with those of other boulders. 
The finest material consisted largely of lath-shaped particles. Many small 
fraofments of vegfetable matter were found in the residue. 
For B 7 I can suggest no relative position with regard to the other 
boulders. Details of its structure will be found on p. 266. It is a very 
puzzling specimen. 
In the other specimens the quantity of terrigenous material is not large ; 
the presence of quartz, mica, and felspar testifies that the deposit was 
not free from terrestrial ingredients, but the lightest part is amorphous 
structureless matter with lath-shaped particles. They are all relatively 
pure chalks. Though the amount of the residue after treatment with acid 
is often considerable, this is probably due to the presence of soluble silica 
derived from siliceous organisms, for all of them except A 5 and 6 contain 
sponge spicules and Radiolaria. Indeed, the successive decrease in the 
amount of material insoluble in acid is an indication of the gradual de- 
crease of the siliceous organisms as well as of terrigenous matter. No 
attempt has been made to arrive at the percentage of the various ingredi- 
ents of the coarse residues. In many of them sand grains, spicules, and 
foraminiferal casts are cemented together by silica in small aggregations 
which can only be separated by a heated solution of caustic potash. None 
of the residues can therefore be taken as strictly representing proportions 
either of organic or terrigenous matter. Fragments of vegetable substance 
occur in many of these residues. 
Other fragments of chalk recovered by the s.s. Goldseeker in dredging 
operations in the North Sea number twenty-four. The largest of these 
measured 44 in. x 3 in. x I J in., and from this they diminished in size to small 
