Correspondence—Prof. E. Hull. 335 
examples. In that paper Dr. Stopes states the supposition that the 
Yarra calcareous nodules are ‘‘more nearly approximate”’ to the 
elay-ironstone nodules of the Carboniferous. I was not aware, how- 
ever, that these contained so large a proportion of woody material as we 
tind in the Yarra nodules, the vegetable remains in the ‘siderites’ 
being usually in the form of impressions or carbonaceous films. The 
proportion of argillaceous matter, moreover, in the nodules from the 
Yarra, is exceedingly small, whilst the amount of calcareous material 
is comparatively large. Since I omitted to give the percentages in my 
paper on the subject, tkey are here appended. From the context of 
that paper it will be apparent that the qualifying term ‘clay’ (only 
once used in connection with these nodules) was a lapsus calamt. 
The analysis of the nodules from the Yarra estuary is as follows :— 
Carbonaceous matter = 55 per cent.; calcareous = 41 per cent. ; 
arenaceous and argillaceous=4 per cent. With regard to the 
occurrence of quartz-grains, zircons, etc., in the Yarra nodules, it 
will be seen on consideration that these are accidental constituents 
of the matrix, due to local conditions, and which would in no respect 
affect the comparison; whilst the solidity and more completely 
ealcified condition of the English ‘coal-balls’ could be accounted 
for by difference in age. 
I have examined a large number of the English ‘coal-balls,’. both 
microscopically and in hand specimens, and had brought with me to 
Melbourne a number of characteristic examples, which I have used 
for comparative purposes. JI am not in a position, however, to 
discuss their relation to the beds in which they occur, since I have 
not examined them 7m siti; and therefore await Dr. Stopes’ detailed 
description with the greater interest. When these results are published 
Wwe may perhaps also learn whether the stems of Calamites and twigs 
of Lepidodendron have been found actually passing from the nodules 
into the surrounding deposits. In conclusion, be the theory proved 
either way, personally speaking it will be equally satisfactory to 
know that the modus operand: of their formation has been successfully 
elucidated. F. Cuapman. 
Nationa Musrum; Mrnpourne. 
April 16th, 1907. 
AN UNPUBLISHED LETTER OF SIR JOSEPH PRESTWICH ON 
SUBMERGENCE OF THE BRITISH ISLANDS IN PLEISTOCENE 
TIMES. 
Srr,—At a time when the views of those who, like myself, hold that 
the partial submergence of the British Isles is the only way in which 
the existence of beds with marine shells of living species can be truly 
accounted for, have been partially discredited by the address of the 
President of Section C at York last year, it may be well to produce 
the following letter of Sir Joseph Prestwich, upon which I have 
accidentally lighted while turning over a book of geological memoranda 
written some years since. In explanation of this letter I may mention 
that it was written in answer to one from myself, in which I called 
