456 TRANSACTIONS OF SECTION c. 
have been preserved in the rocks representing the great time-gap between the 
Ordovician and Jurassic formations. 
In this connection Professor Seward remarks’ : ‘It is reasonable to prophesy 
that further researches into the structure of ancient limestones will considerably 
extend our knowledge of the geological and botanical history of the Coralli- 
nacee.’ This prophecy has been amply fulfilled, especially as regards this 
particular genus, and recent discoveries go far towards filling the previously 
existing gaps in our knowledge of the vertical distribution of this interesting 
genus. 
Thus the recent detection in the lowest Cambrian rocks of the Antarctic 
Continent of a form which appears to be referable to this genus enables us to 
trace the ancestry of Solenopora back almost to the earliest rocks in which 
fossils have yet been discovered, while the gap in the succession which pre- 
viously existed between the Ordovician and Jurassic forms was decreased by the 
description in 1908 by Professor Rothpletz of a new species Solenopora got- 
landica, from the Silurian rocks of Farée Islands in Gotland.* A large number 
of deposits, however, still remained, between the Gotlandian and lower Jurassic 
beds, from which no example of Solenopora had so far been recorded. 
The identification, therefore, a few years ago, by Dr. G. J. Hinde, of examples 
of this genus from among the nodules I had collected from the Shap dolomites, 
is of considerable interest, as the presence of Solenopora in the lower Car- 
boniferous rocks of this country materially decreases the gap in our knowledge 
of the succession of forms belonging to this genus, which had previously 
existed. 
Girvanella. 
This organism, which is now known to be widely distributed in the 
Paleozoic and Mesozoic rocks of this country, was originally described in 
1878 by Nicholson and Etheridge, jun., from the Ordovician rocks of the Girvan 
district. The genus was established to include certain small nodular structures 
composed of a felted mass of interlacing tubes, having a width of 10 and 18 yn, 
the cells being typically simple, imperforate tubes without visible internal 
partitions. The geno-type, G. problematica, was, however, at that time referred 
to the Rhizopods and regarded as related to the arenaceous foraminifera.® In 
1888 Nicholson, in redescribing this genus in the Geological Magazine, compares 
Girvanclla with the recent form Syringammina fragillissima of Brady. 
More recently Mr. Wethered has shown that an intimate association 
frequently exists between Girvanella tubes and oolitic structure, and he has 
described several new species of Girvanella, from the Paleozoic rocks and also 
from certain Jurassic limestones. 
The reference of Girvanella to the Calcareous Algw, though not yet sup- 
ported by incontestable evidence, has been advocated by several writers in 
recent years. Even as long ago as 1887, Bornemann, in describing examples 
of Siphonema (Girvanella Nich.), which he had discovered in the Cambrian 
rocks of the Island of Sardinia, suggested that this organism might belong 
to the Calcareous Alge. 
In 1891 Rothpletz ’° noticed that some of the specimens of Girvanella which 
he had examined were characterised by dichotomous branching of the tubes; 
on this account he removed the genus from the Rhizopods to the Calcareous 
Alge, placing it provisionally among the Codiacew. Three years later Dr. A. 
Brown, in summing up the evidence in favour of the inclusion of Solenopora 
among the Nullipores, expressed the opinion that Girvanclla might ultimately 
come to be regarded as referable to the Siphonee Verticillate. 
In 1898, however, this genus was still only doubtfully placed with the 
Calcareous Algz, for Seward, in his work on fossil plants,’* remarks : ‘ The nature 
of Girvanella, and still more its exact position in the organic world, is quite 
uncertain. . . . We must be content for the present to leave its precise nature 
7 Fossil Plants, vol. I., p. 190, 1898. 
8 Kungl. Svenska. Vets. akad. Handl. Bd. 43, No. 5, 1908, p. 14, pl. iv., pp. 1-5. 
9 Silurian Fossils in the Girvan District, 1878, p. 23. 
10 Zeitsch. d. D. Geol. Gesell., 1891. 1 Op. cit. (7), p. 125. 
