530 E. Wether ed — Organisms in Carboniferous Limestone. 



like what Prof. Hull describes as occurring in " northern districts." 

 They were first described by Mr. W. 0. Lucy, F.G.S., 1 and later on 

 by myself. 2 Stage B is represented by the Carboniferous Limestone, 

 or middle series, but appears to be quite void of fossil remains, which 

 fact I shall refer to later on. Above stage B, Professor Hull gives, 

 as stage C, the Yoredale Series, and he describes them as "shales and 

 grits, passing downwards into dark shales and earthy limestones." 

 In the Forest of Dean we have beds very similar in a lithological 

 point of view to those which Prof. Hull described ; but in my pre- 

 vious paper, just referred to, objection was taken to my classing 

 these upper limestones as the representatives of the Yoredale Series. 

 I shall not in this paper discuss that question, but I shall show that 

 these upper limestones are different from the Carboniferous Lime- 

 stone, and are quite as much entitled to be grouped separately as the 

 Lower Limestone Shales. To condense what I have said, the Car- 

 boniferous Limestone series in the Forest of Dean consists of the 

 following divisions : — 



Approximate thickness in feet. 

 Upper Limestones (occupying position of Yoredale Series 



of the North of England.) Stage C. 116 3 



Carboniferous Limestone proper. Stage B. ... ... 360 



Lower Limestone Shales. Stage A. ... ... ... 130 



Lower Limestone Shales. 



The calciferous sandy beds, which succeed Old Bed Conglomerate, 

 gradually become more calciferous in ascending order, till at last 

 a series of quarries are found opened out in a succession of limestones 

 and shales. Some of the latter are bituminous, a feature to which 

 I have called attention in a paper communicated to the Cotteswold 

 Club. 4 The lowest of these beds are exposed in two quarries on 

 either side of the deep cutting near Drybrook, from which the 

 following specimens were selected (see Plates XIV. and XV.). 



No. 1 (Plate XIV. Fig. 1). — Acrinoidal limestone which gave the 

 following result on chemical analysis : — 



Insoluble in acid { Insoluble residue (Sand) ... 

 ( Organic matter 



! Carbonate of Lime ... 

 Carbonate of Magnesia ... 

 Carbonate of Iron 

 Alkalies 



3-68 

 3-30 



90-40 



2-38 



•42 



trace 



100-18 



The sand is little else than grains of quartz as large as '01 of an 



inch in diameter, but average about "003. The larger ones are 



rounded, the smaller ones angular. The absence of alumina in the 



analysis is a feature to be noticed, as in the analysis of a crinoidal 



1 Proc. Cotteswold Club, 1866. 



2 Quart. Journ. Geol. Soc. vol. xxxix. p. 212, 1883. 



3 I put the Upper Limestone at 1 1 6 feet, but it is impossible to measure the thick- 

 ness accurately at present. The Wilderness Portland Cement Company, however, is 

 making a cutting, near Mitch eldean, with the object of ascertaining the thickness, as 

 the limestone produces a good cement. 



4 " On the Occurrence of Spores of Plants in the Lower Limestone Shales of the 

 Forest of Dean," Proc. Cotteswold Club, 1883—1884, pp. 168—173. 



