458 TRANSACTIONS OF SECTION C. 
study of numerous thin sections from the Lower Carboniferous rocks of the 
north-west of England has revealed the presence of several distinct organisms, 
nee will, I think, eventually be found to be referable to the Calcareous 
ge. 
This meagre list appears to exhaust the genera known at the present time 
from the Lower Carboniferous rocks of Britain; and the only lime secreting 
plant so far recorded from the Mesozoic and Tertiary rocks of this country (if 
we except Rothpletz’s sub-genus Solenoporella) is Chara from the Wealden 
beds of Sussex, the uppermost Jurassic of the Isle of Wight and Swanage, 
and the Oligocene of the Isle of Wight. 
Outside of this country the literature on fossil Calcareous Alge is much 
more extensive. The interest originally aroused on the Continent by the 
writings of Phillipi, of Unger of Vienna, Cohn, Rosanoff, Giimbel, Saporta, and 
Munier-Chalmas has been further maintained in our own time by Bornemann, 
Steinmann, Frith, Solms-Laubach,*® Rothpletz, Walther, Kiaer, and others; 
while the more favourable conditions which obtained for the growth of these 
organisms, especially during Silurian, Triassic, and Tertiary times, has afforded 
a much wider field for their observation. 
Thus, in addition to the forms recorded from this country, an important 
part has been played by members of the family of the Dasycladacee, together 
with such genera as Spherocodium, Lithothamnion, and Lithophyllum. 
It is now time to consider the part played by these organisms in the formation 
of the sedimentary rocks through the successive geological periods. 
ARCH HAN, 
In the Archean rocks no undoubted remains of algz# have yet, so far as 1 
am aware, been recorded, but Sederholm considers that certain small nodules 
in the Archean schists of Finland may represent vegetable remains. I may 
also perhaps here refer to some curious oolitic structures which I met with in 
Spitsbergen in 1896 when examining the rocks of Hornsund Bay. These 
oolites occur on the south side of the Bay, and are closely connected with 
massive siliceous rocks which may represent old quartzites. The whole series 
is much altered, and detailed structure cannot now be made out. The rocks 
occur apparently stratigraphically below the massif of the Hornsund Tinde, and 
may belong either to the Archean or the base of the Heckla Hook series. As, 
however, similar rocks have not been recorded from the type district of Heckla 
Hook, they may be referred provisionally to the Algonkian, and may represent 
the quartzites and earthy limestone of the Jotnian series of Scandinavia. 
They are mentioned here in connection with Mr. Wethered’s view that oolites 
are essentially associated with the growth of Girvanella. 
CAMBRIAN. 
Passing on to the Palwozoic rocks, we find in the Cambrian deposits very 
few indications that Calcareous Algz played any considerable part in their 
formation. 
This is no doubt due, to some extent, to the conditions under which these 
deposits accumulated in the classical localities where true calcareous deposits are 
typically absent. In the Durness limestone, however, where considerable 
masses of dolomites occur, the conditions would appear at first sight to have 
been more suitable for the growth of these organisms; but even here the slow 
rate of accumulation and the large amount of contemporaneous solution may 
have militated against their preservation. At the same time, it is possible 
that a systematic search in the calcareous facies of the Cambrian rocks in the 
north of Europe and America may result in the discovery of the remains of 
some members of this group. That there is ground for this suggestion is 
shown by recent work in the Antarctic Continent. i 
Professor Edgworth David and Mr. Priestly have discovered among the 
rocks on the north-west side of the Beardmore Glacier dark grey and 
pinkish grey limestone containing the remains of Archzeocyathine, Trilobites, 
and sponge spicules, together with abundant remains of a small Calcareous 
16 Fossil Botany, Oxford, 1891. 
