Dr. Wheelton Hind — The Toredale Series. 211 



argument, of course, applies equally well to those beds wliich have 

 the typical Carboniferous Limestone fauna. 



Now, if carried to its ultimate conclusion, the fact of the presence 

 of these beds containing a Carboniferous Limestone fauna at various 

 horizons in the Black Shales (Congleton Edge), the Millstone Grit 

 (Sawley, near Eipon), the Lower Coal-measures (the roof of the 

 Bullion Coal), and in the Coal-measures themselves (the Penneystoae 

 of Coalbrookdale, the roofs of the Gin Mine and Bay Coal, North 

 Staffordshire), emphatically proves Sir Andrew Eamsay's contention 

 that the Carboniferous system was one great succession without 

 a break ; because the fauna characteristic of its lowest beds survived 

 during the whole of its duration, a few species probably being 

 preserved into Permian times. But, notwithstanding this unity, 

 there is a well-marked line along which a division can be made 

 into Upper and Lower Carboniferous, for which there are strong 

 grounds, both lithological and palgeontological, that is, where lime- 

 stones of typical marine chai-acter ceased to be deposited, and shales 

 and grits with coals took their place, denoting a shallower water 

 and more frequent return to terrestrial conditions, and containing 

 a fauna for which these conditions were suitable. 



I have shown in the introduction to my Monograph on the British 

 Carboniferous Lamellibranchiata (Pal. Soc, vol. l, 1895, pp. 10-15) 

 that the Carboniferous series as developed in Great Britain and also 

 ia Europe and North America, lend themselves best to a twofold 

 classification, which I have summarized as Upper Cakboniferous 

 or Anthraciferous, and Lower Carboniferous or Calcareous series ; 

 and I need not enter further into detail here. 



This base line of the upper division would, in Derbyshire, North 

 Stafibrdshire, and Yorkshire, be at the top of the uppermost thin 

 limestone ; for in a few localities the massif of Carboniferous Lime- 

 stone was succeeded by a short series of passage beds, containing 

 thin limestones with a Carboniferous Limestone fauna, e.g. Butterton 

 Moor, near Leek (Proc. Geol. Assoc, vol. xi, pp. cxxxi, cxxxii) ; and 

 in the Wensleydale district and Northumberland the topmost bed 

 of limestone would also form the limit, and this line of division is 

 really a palaeontological one, and not lithological, because it is at 

 this horizon that the characteristic fauna of the Carboniferous 

 Limestone series ceases to be persistent. The beds above the 

 limestones would then be Upper Carboniferous, and would include 

 the shales below the grits, the grits, and Coal-measures, characterized 

 by faunas No. 1 and No. 2. 



There is a great similarity between the deposits of this series, 

 there being several workable coal-seams in the grit series, and 

 many beds of coarse sandstone in the Coal-measures ; and in addition,- 

 the whole of this series is characterized by an absence, with rare 

 exceptions, of marine conditions. There occur frequent interruptions 

 in deposit due to terrestrial conditions, and, moreover, the palaeon- 

 tology of this series is as a whole very different from that which 

 obtains in the beds below, and is peculiarly characteristic of it. 



Some objection may be taken to this division from the fact that 



