TRANSACTIONS OF SECTION C. 793 
cracked, and, syenite being injected, the white band described by the authors was 
produced in exactly the situation one would have expected to have found it. 
The plate structure of this white band being continuous with that of the in- 
closing shonkinite is not an objection to its dyke-like nature, for there are several 
ways in which such cleavage may be developed. 
At any rate the presence of this white band is quite inexplicable on the 
‘ segregation’ or ‘liquation’ hypothesis, and is the insurmountable obstacle to 
the acceptance of Messrs. Weed’s and Pirrsson’s generalisations as to magmatic 
differentiation. 
SATURDAY, SEPTEMBER 19. 
The following Papers and Reports were read :— 
1. The Depths of the Sea in Past Epochs. By E. B, WeTueRen, F.G.S. 
The author referred to the teachings of Hutton that the past history of our 
planet is to be explained by what we see going on at the present time. ‘Till the 
reports of the ‘Challenger’ Expedition were published our knowledge of the 
‘depths of the sea’ was very meagre, and the teachings of Hutton could not be 
applied for want of this knowledge. After reading thé report on ‘ Deep Sea 
Deposits,’ by Mr. Murray, it occurred to the author that it would be of interest to 
study in detail the ‘ Depths of the Sea in Past Epochs,’ so far as possible, by a 
microscopic examination of limestones which contain what is preserved of the 
fauna of the sea in which these rocks were formed, and thus to further test the 
teachings of Hutton. 
The author has, however, only accomplished a small part of the work indicated, 
and in this paper he only gives an outline of his investigations so far done. 
Commencing with the Wenlock Limestone of the Silurian system, the author 
referred to the leading fossils, and remarked on the very fragmentary condition cf 
the calcareous remains which have contributed to the building up of this limestone. 
Judging by the high percentage of detrital matter in the rock, in one bed amount- 
ing to 30°4 per cent., he thinks that land was not far off, and therefore the shells 
and skeletons of marine creatures may have been subjected to the action of waves, 
which would account for the fragmeutary condition in which they were finally 
deposited on the floor of the sea. 
Reference was next made to the work of encrusting organisms which had not 
been pointed out prior to the author’s researches. In some beds of the Wenlock 
Limestone the majority of the organic calcareous fragments are partially or entirely 
inclosed by a crust which was the work of the little-understood genus Girvanella. 
This organism consists of a minute calcareous tube, as small as ‘01 of a millim. 
in diameter, with well-defined walls. So important has been the work of this 
tubular form of life that the crusts produced by the growth and multiplication of 
the tubules have in some cases become the chief factor in building up beds of 
limestone. 
Passing to the Carboniferous period, the author referred to the known fact that 
mollusca, corals, crinoids, polyzoa, &c., were very numerous in the sea of this epoch, 
and their shells and skeletons have contributed to the calcareous deposits which 
accumulated on the floor of the Carboniferous sea, which deposits are now known 
as the Carboniferous Limestone. It is, however, an error to suppose that the 
remains of these creatures were the chief constituents of the calcareous deposits in 
the depths of the Carboniferous sea. If the great central mass of the Carboniferous 
Limestone be examined microscopically, it will be found that the tests of micro- 
scopic life form the material with which this strata has been built up. Indeed, 
microscopic life must have been quite as abundant in Carboniferous waters as it 
Was in the sea in which the chalk was formed, and not unlike what we find at the 
_ present time. We know that the chalk is largely built up of the remains of 
_ Foraminifera, and the calcareous ooze drawn up from the Atlantic has been proved 
1896. 3 F 
