330 Reports and Proceedings—Geological Society of London. 
Dr, A. Osann,1 the bulk analysis is re-calculated free from water, then 
the molecular proportions and percentages are calculated, etc. As 
a result Dr. Grubenmann proposes 12 groups: (1) Alkali felspar 
gneisses, (2) Silicate of alumina gneisses, (3) Lime soda-felspar 
gneisses, (4) Eclogites and Amphibolites, (5) Magnesian silicate 
schists, (6) Jadeite rocks, (7) Chloromelanite rocks, (8) Quartzite 
rocks, (9) Lime silicate rocks, (10) Marbles, (11) Iron-oxide rocks, 
(12) Aluminium oxide rocks, ‘Each group is (where possible) divided 
into three subdivisions in accordance with the three zones of 
metamorphism proposed in the first volume. The greater part of the 
volume is occupied by detailed descriptions of the rocks illustrated by 
48 photographie figures of microscopical sections, the only fault of 
which is that the minerals represented in each section are not always 
indicated. 
Although less interesting reading than the first volume the second 
is likely “to be of more practical use. Both volumes have the 
drawback of being without an index. An author who introduces 
new terms and leaves one to laboriously search for them handicaps 
himself. Again, who can tell, @ prior, that the well-known Saxon 
granulites are to be looked ioe in ‘‘Die Familie der Biotitarmen 
Kata-Orthoklasgneisse’’ ? An index would enable one to find them 
at once. B. Hozson. 
REPORTS AND PROCHEHDINGS. 
I.—GeotogicaL Soctnty or Lonpon. 
I.—May 1st, 1907.—Sir Archibald Geikie, D.C.L., Se. Ds, ‘Secskhtss, 
President, in the Chair. 
The following communications were read :— 
1. ‘‘On the Xerophytic Character of Coal Plants, and a suggested 
Origin of Coal Beds.”’ By the Rey. Professor George Henslow, M.A., 
F.U.S., 2.G.S. . 
Of the Paleeozoic flora, the Hguisetites, now represented by the sole 
genus Lguisetum, are decidedly hygrophytic, if not hydrophytic. The 
Ferns, which appear to have much resemblance to certam modern 
types, especially the Marattiee, seem to have lived under more or 
less similar conditions to the present; that is, varying from the 
hygrophytic habit of Hymenophyllum to the xerophytic Ceterach. 
The Cycadofilices, Cordaites, etc., are decidedly xerophytic; and the 
same is the character of the Lycopodiales, represented now by 
Lycopodium and Selaginella, and of Psilotum, Salisburia, and others. 
In fact, the characteristic feature of the great coal forests was 
xerophytic, and the vegetation appears to be of an upland type. 
Iilustrations are given from recent and Carboniferous plants, to show 
the characters of leaf, root, and stem which separate these classes of 
plants. The position of coal-seams is accounted for by the action of 
1 Tschermak’s Min. und Pet. Mitteil., xix (1900), p. 351. 
