﻿Geological Society of London. 283 



between the Carboniferous Limestone and the overlying Yoredale 

 series'^ were sufficient to justify their separation into distinct divi- 

 sions ; while the Yoredale, Millstone Grit, and Gannister series, are 

 I'elated by close mineral and paleeontological resemblances. 



With a view, therefore, of bringing the classification of the Car- 

 boniferous series into harmony with the character of the repre- 

 sentative faunas, 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 fauna being essentially of fresh water. The 

 series, as thus amended, would be as follows : — 

 Upper Carbonifbeous Group. 

 Stage G. Upper Coal-meusures ) Essentially 



„ P. Middle Coal-measures ^freshwater. 



Middle Carbonifekous Group^ 



Stage E. Lower Coal-measures or Gannister Beds \ -p ,• ■., 



,, D. Millstone-Grit series 1 m •' 



„ C. Yoredale series ., ) 



Lower Carboniferous Group. 



Stage B. Carboniferous Limestone series ] Essentially ma- 



„ A. Lower shales, slates, carboniferous and ealciferous and [ rine (except 

 sandstone series ) in Scotland). 



The author then proceeded to show, by reference to the writings 

 of Dr. F. Eomer of Breslau, of M. De Koninck, 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. 



In this paper the author endeavoured to explain the mode of pro- 

 duction of pebbles of coal in the claj^s 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 formei'ly 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 distributed the grains of sand 

 and other materials upon the coal-seam. 



IL— May 9th, 1877.— Prof. P. Martin Duncan, M.B., F.E.S., 



President, in the Chair. 



1. " On the Agassizian Genera Amhhjpterus, Paloeoniscus, 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 characters by 



1 In the south of Ireland there is strong evidence that the Yoredale beds (" Shale- 

 series ") are unconformable to the Carboniferous Limestone. 



