283 
Geological Society of London. 
between the Carboniferous Limestone and tlie overlying Yoredale 
series 1 were sufficient to justify their Separation into distinct divi- 
sions ; wbile the Yoredale, Millstone Grit, and Gannister series, are 
related by close mineral and palaeontological resemblances. 
Witli a view, tlierefore, of bringing the Classification of the Car- 
boniferous series into harmony with the character of the repre- 
sentative faimas, and the physical features of the successive stages, 
the author suggests that Stages C, D, and E, composed of essentially 
marine beds, should be United into a Middle Carboniferous group ; 
while Stages F and G would remain as at present, in the Upper 
Carboniferous, their fauma being essentially of fresh water. The 
series, as thus amended, would be as follows : — 
• Upper. Carboniferous Group. 
Stage G. Upper Coal-measures 1 Essentially 
„ F. Middle Coal-measures \ freshwater. 
Middle Carboniferous Group. 
Stage E. Lower Coal-measures or Gannister Beds 
„ D. Millstone-Grit series 
„ C. Yoredale series 
Lower Carboniferous Group. 
Stage B. Carboniferous Limestone series 1 Essentially ma- 
„ A. Lower shales, slates, carboniferous and calciferous and : rine (except 
sandstone series ) in Scotland). 
The author then proceeded to show, by reference to the writings 
of Dr. F. Römer of Breslau, of M. De Köninck, M. Charles Barrois, 
etc., that Stage E with its marine fauna is represented both in 
Germany, Belgium, and France, as well as in the British Islands, 
so that the Classification would hold good over Western Europe, 
which was a sufficiently extensive area to justify the establishment 
of a distinct group of strata. 
2. “ On Coal-pebbles and their Derivation.” By H. K. Jordan, 
Esq., F.G.S. 
ln this paper the author endeavoured to explain the mode of pro- 
duction of pebbles of coal in the clays and sandstones of the South 
Wales Coal-field and elsewhere, the occurrence of which had been 
long since noticed by Sir William Logan and Sir Henry de la Beche. 
His opinion is that the pebbles in question are derived either from 
the seam of coal above which they are found, or from a seam of 
coal which formerly existed in the same, or approximately in the 
same position, and which has been destroyed by erosion, the effect 
of strong currents of water, which distrihuted the grains of sand 
and other inaterials upon the coal- seam. 
II. — May 9th, 1877. — Prof. P. Martin Duncan, M.B., F.R.S., 
President, in the Chair. 
1. “ On the Agassizian Genera Amblypterus, Palceoniscus, Gyro- 
lepis, and Pygopterus.” By Eamsay H. Traquair, Esq., M.D., 
F.R.S.E., F.G.S. 
The author’s object in this paper was to discuss the cliaracters by 
1 In the soutb of Ireland there is strong evidence that the Yoredale beds (“ Shale- 
series ”) are unconformable to the Carboniferous Limestone. 
) Essentially 
j Marine. 
