Reports and Proceedings—Greological Society of London. 89 
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GeotocicaL Society or Lonpon. . 
I.—December 6, 1882.—J. W. Hulke, Esq., F.R.S., President, in 
the Chair.—The following communications were read :— 
1. “Note on a Wealden Fern, Oleandridium (Teniopteris) Bey- 
richit, Schenk, new to Britain.” By John E. H. Peyton, Ksq., F.G-.S. 
This fern, figured by Schenk in the ‘‘ Paleeontographica’”’ (vol. xix. 
plate xxix. figs. 6, 7), was discovered near Minden, in the North-west 
German Wealden-beds, and appears to have been hitherto unknown in 
England. It was first discovered in the Wadhurst Clay (‘‘ Tillgate 
stone”’ of Mantell) of the cliffs east of Hastings, by Mr. Charles 
Dawson, of Warrior Terrace, St. Leonards, who has a fine collection 
of Wealden fossils, and was brought to my notice by Professor 
Augusto de Linares, of the Valladolid University, who has lately dis- 
covered the Wealden in the North of Spain. 
This specimen, which I have much pleasure in presenting to the 
Society for their Museum, I found about a fortnight ago, also in our 
local ‘‘ blue-stone’’ from the Wadhurst Clay of the Hastings cliffs. 
_In connexion with the flora of the Wealden, I may perhaps men- 
tion that, besides the ordinary ferns recorded by Mantell, Fitton, 
Topley, and others, viz. ZLonchopteris Mantelli, Sphenopteris gracilis, 
S. Mantelli, 8. Phillipsii, S. Sillimani, etc., I have been fortunate 
enough to discover the following North-German forms :—Pecopteris 
Geimitzi, Pecopteris Murchison’, Pterophyllum schaumburgense (Dunker), 
and an undetermined one, which I think is Sphenopteris Gapperti. 
They all occur in the beds of stone in the Wadhurst Clay, which are 
locally used for building and road-metal. 
2. “On the Mechanics of Glaciers, more especially with Relation 
to their Supposed Power of Excavation.’? By Rev. A. Irving, B.A. 
1. The author commenced by showing that ice is comparable in 
Some respects with glass, with which (at temperatures not far removed 
from their several points of liquidation) it has many points of physical 
resemblance, the chief point of difference between the two bodies being 
the absence in ice of the great ductility which characterizes glass. 
Ice may therefore be regarded as a near approximation to the “vitreous 
condition”’ of water. 
2. The remarkable yielding property (‘ plasticity,” ‘‘ Nachgiebig- 
keit”’) of ice as it exists in glaciers (which constitutes its most im- 
portant point of resemblance to heated glass) being recognized asa 
fact of observation (the experiments of Tyndall and Helmholtz, and 
the measurements of glacier-movements by the former being reterred 
to), the deduction drawn from these facts (irrespectively of the theo- 
retical explanation of the facts themselves) in the light of the simple 
law of conservation of energy, is that in the movement of glaciers only 
a small residuum of ‘‘energy of motion” of the glacial mass is avail- 
__' It varies slightly from the one figured by Schenk in the nervures; and the mid- 
rib is ‘‘herring-boned.’”’ It bears a strong resemblance to Teniopteris vittata 
(Brongn.) of the Trias (Geikie’s ‘ Text-Book of Geology,’ fig. 358) ; compare also 
L. scitaminee-folia (Sternberg), from the Stonesfield beds (Phillips’s ‘ Geology of 
Oxford,’ Diagram xxx. fig. 8). 
