E. Wethered — Organisms in Carboniferous Limestone. 531 



limestone from the Lower Limestone Shales from Clifton the late 

 Mr. Stoddart also called attention to the absence of alumina : he 

 remarks, 1 " The absence of alumina in these beds is very remarkable, 

 because the Lower Limestone Shales are very argillaceous." The 

 organic remains preserved in this bed are chiefly those of Crinoids, 

 associated with Polyzoa, the spines of Spirifera and Productus ; 

 in some layers the two latter are very numerous. 



No. 2. — A light blue hard compact limestone, almost entirely made 

 up of the valves of Ostracoda, but there are also present a few 

 Polyzoa, the spines of Brachiopoda, and Spirorbis carbonarius. In 

 the majority of cases the valves of the Ostracods are broken into 

 fragments, but where preserved the largest measure '035 of an inch 

 in diameter. The remains are cemented together by crystalline 

 calcite, and the empty valves are also filled with the same mineral. 



No. 3. — A slightly ferruginous limestone. The organic remains 

 are not well preserved ; those which can be determined consist of 

 joints of Crinoids, remains of Polyzoa, valves of Ostracods and ob- 

 scure calcareous fragments. 



No. 4. — A dark argillaceous bed containing 17-15 per cent, of 

 organic matter, 6*89 of which was volatile. On washing a sample 

 with distilled water, a large quantity of mud is got rid of, and the 

 residue consists of quartz-grains, fragments of shells, plant-remains, 

 and the jaws of Annelides. 



No. 5. — A concretionary limestone slightly oolitic, the nuclei of the 

 granules are grains of quartz. There are also present the valves of 

 Ostracods, joints of Crinoids, and the remains of a small Coral. 



The next specimens were selected from a quarry a little beyond 

 the last in the direction of Mitcheldean, in which beds were exposed 

 occupying a higher horizon than those in the previous quarry. 



No. 6. — Prom a thickness of about 10 feet of thin strata, slightly 

 ferruginous ; on exposure to the air, the carbonate of iron (in which 

 state the iron exists) undergoes decomposition, ferric oxide is formed 

 which imparts a yellow tinge to the rock. The structure exhibited is 

 chiefly that of calcareous sand, among the grains of which are frag- 

 ments of shells. The spaces between the sand are filled in with calcite. 



No. 7 (PI. XIV. Fig. 3). — A bed of argillaceous limestone 3| inches 

 thick, and contains 11*15 of sand. It is made up of the valves of 

 Ostracods, occasionally Polyzoa, scanty fragments of Crinoids, and 

 oolitic granules. As in the previous examples, the limestone is con- 

 solidated by an infilling of calcite. 



No. 8. — A dark argillaceous limestone 8| inches thick, and con- 

 taining 164 per cent, of sand. The calcareous constituents comprise 

 the spines of Spirifera, broken valves of Ostracods, and other remains 

 which are too obscure to be determined ; some were probably de- 

 composed and altered shell fragments. 



No. 9. — Light brown arenaceous limestone, 6 inches thick, con- 

 taining 37-2 per cent, of sand in quartz grains, measuring 'OOl of an 

 inch in diameter. Microscopic sections show the valves of Ostracods, 



1 Ann. Mag. Nat. Hist. vol. viii. 3rd series, p. 487. 



