532 E. Wethered — Organisms in Carboniferous Limestone. 



numerous spines of Spirifera, fragments of shells, etc. The vacant 

 spaces are filled in with calcite. 



No. 10. — A bed of blue argillaceous limestone 6 inches thick ; 

 contains 16*75 per cent, of sand, the grains of which ai - e rounded 

 and measure about '004 of an inch in diameter. The rock is chiefly 

 made up of the spines and other remains of Brachiopoda and numerous 

 valves of Ostracods. 



No. 11. — A black argillaceous bed 5| inches thick with calcareous 

 arenaceous layers. In the argillaceous material the joints of Crinoids, 

 remains of a small variety of Rhynchonella pleurodon and Ostracods 

 were discovered. Sections of the thin calcareous layers showed them 

 to be largely made up of the spines of Spirifera, a few joints of 

 Crinoids, and calcareous fragments. 



No. 12. — An earthy limestone 5 inches thick ; contains 12 per 

 cent, of sand, the grains of variable size, the largest measuring "008 

 and the smallest *002 of an inch in diameter. The limestone is 

 largely made up of an organism to which I shall provisionally give 

 the name of Mitcheldeania (PL XIV. Fig. 6), and which I shall 

 describe further on. The rock also contains some Ostracoda. 



No. 13 (PI. XIV. Fig. 4). — A light limestone 8 inches thick, con- 

 taining 3-2 per cent, of sand, the grains measuring *003 of an inch 

 in diameter. Flakes of mica and fragments of other minerals are 

 also present. The bed contains the remains of Mitcheldeania, a few 

 Polyzoa, a large proportion of Ostracoda, and a shell which Mr. 

 Etheridge, F.R.S., tells me is allied to Murcliisonia angnlata. 



PL XIV. Fig. 4 represents a portion of the rock in which the 

 valves of Ostracods are the chief feature. The clear calcite is well 

 shown filling up the empty valves and spaces between them. 



No. 14. — Similar to the last, with the exception that Mitcheldeania 

 is less numerous. Thickness 1 foot 6 inches. 



No. 15 (PL XIV. Fig. 5). — Made up of various small concretions, 

 of various shapes ; calcareous fragments and occasional spines of 

 Spirifera. Thickness 2-| inches. 



No. 16. — A limestone 1 foot 3 inches thick. Chiefly concretionary, 

 with the spines of Froductus, Crinoidal remains, and other calcareous 

 fragments. 



No. 17. — A black argillaceous bed 4 inches thick, containing 5*13 

 per cent, of sand, the quartz grains measuring *004 of an inch in 

 diameter. Flakes of mica and fragments of other minerals also present. 



No 18. — A light argillaceous limestone 7 inches thick, containing 

 16-5 per cent, of sand, the quartz-grains varying between *009 and 

 •001 of an inch in diameter. The organic remains are chiefly those of 

 Ostracods, well preserved and capable of being extracted from the 

 matrix. 



No. 19. — A shelly limestone 15 feet thick, and containing 39"2 per 

 cent, of sand. The chief calcareous constituents are the remains of 

 shells, and those in a very fragmentary condition. 



General Review op the Lower Limestone Shales. 



The samples examined are sufficient to give a correct idea of the 



