566 Notices of Memoirs—E. Wethered—Lr. Carboniferous. 
so-called Lower Limestone Shales. In the Forest of Dean the lime- 
stones are largely made up of the valves of Ostracoda, among which 
the following have been determined: Kirkbya variabilis, K. 
plicata, Cytherella extuberata, Bythocypris sublunata, and Darwinula 
berniciana (?). Among the other fossils which are numerous may 
be mentioned Athyris Royssii, Rhynchonella pleurodon, Encrinites, and 
Polyzoa. Among the latter the following have been determined : 
Rhabdomeson gracile, Phill., and Fenestella tuberculocarinata, Ether. 
jun. In the Lower Limestone Shales of the Bristol Coal-field 
Ostracoda are not so plentiful, though in some beds the valves of 
these small Crustacea are numerous. Rhynchonella pleurodon, Athyris 
Royssii, Productus, Spirifera, Crinoids, and Polyzoaoccur. At Clifton 
the Lower Shales are followed by a Crinoidal Limestone known as 
the Black Rock, which is about 490 feet thick and is not represented 
in the Forest of Dean. The Black Rock series are followed by 
70 feet of Dolomite, and then by about 100 feet of white ooclitic 
limestone which the author regards as the true base of the Middle 
or Carboniferous Limestone. The author has grouped the Lower 
Limestone Shales with the Black Rock under the term Lower Lime- 
stones, and he considers the stage to occupy the horizon of the 
Tuedian and Calciferous series of the North of England and Scotland. 
As to the sandy beds which lie between the Old Red Conglomerate 
and Lower Limestone Shales, the author regards them as the equiva- 
lent of the lower portion of the Transitional series of Phillips and 
the Calciferous of Scotland. The true upper limits of the Old Red 
Sandstone should be drawn at the Old Red Conglomerate. 
As to the Middle Limestone there can be no doubt that it is the 
equivalent of the Carboniferous Limestone as generally understood, 
a term which the author thinks objectionable, and he would term 
the whole series Carboniferous Limestone. The Middle Limestone 
is largely made up of Foraminifera and Calcisphera, but Corals, 
Polyzoa, Crinoids, and shells occur, sometimes in quantity. In the 
Forest of Dean the Middle Limestone is extensively dolomitized. 
Coming to the Upper Limestones ; at Clifton it is difficult to draw 
the line at which the series should commence, as there is little 
alteration in the structure from that of the Middle Limestones. 
Corals are more numerous, coarse oolitic beds appear, and the beds 
become mixed with Millstone-grit. In the Forest of Dean the upper 
stage is well and clearly defined by two characteristic limestones 
known as ‘Crease’ and ‘Whitehead.’ The former of these has 
become partially crystallized, but in some beds shells of Productus are 
numerous, and also Calcisphere. 
The Millstone-grit is about 900 feet thick in the Bristol Coal-field, 
and is a hard, slightly pink-coloured quartzite. In the Forest of 
Dean it is about 270 feet, and is a loose yellow, red and mottled 
sandstone made up of well-rounded grains of quartz. The lowest 
beds are argillaceous, and contain remains of Lepidodendra. 
