20 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 2, 



bed of mud resting upon them, and which is now the underclay of 

 a bed of coal. This coal was next submerged under the conditions 

 required for bituminous limestone and Modiola-shale. The Mo- 

 diola-waters were then filled up with clay and sand, the latter rip- 

 ple-marked, and with drifted vegetable fragments. Another soil was 

 formed above these beds, and on it we find an inch of coal, with 

 flattened Sigillarice, which probably once grew on the underclay. 

 This terrestrial surface was succeeded, as usual, by waters swarm- 

 ing with Modiolce and fish, and on these were spread out beds 

 of sand and mud, with ripple-marks, drift-trees, and evidences of 

 partial denudation by currents. A terrestrial surface was again re- 

 stored, and 4 inches of coal were accumulated ; but the waters again 

 prevailed, and in the coal itself we find Modiolce, Cypris, and plants 

 covered with Spirorbis, indicating that these creatures took possession 

 while the vegetable matter was still recent, and probably much of it 

 in an erect position. A terrestrial surface was, however, soon restored ; 

 for in the shale which covers the coal there is a fine ribbed stump, 

 2 feet in diameter, and displaying on its roots the markings of the 

 true Stigmaria ficoides, as well as the rootlets m situ in the shale. 

 This is the first instance we have here yet met with of the distinct 

 coimection of an erect ribbed stem with its Stigmaria-roots. The causes 

 of the difficulty of observing the roots and stem in connection will 

 be stated in the sequel. 



The next group is probably the result of somewhat rapid mecha- 

 nical deposition. Its lowest bed is a thick sandstone, deposited by 

 currents which have undermined wooded banks, or passed through 

 recently submerged forests, for it contains numbers of trunks of dif- 

 ferent trees, retaining their bark and surface-markings. In the 

 succeeding 1 1 feet of sandstone and shale, I have noted but one 

 underclay, supporting only a thin carbonaceous layer, which may, 

 however, have been a soil for a long time. There are, however, erect 

 trees and Calamites at three levels ; and one of the trees springs 

 from a shale loaded with Poacites which may have grown around 

 its base. 



The next Group (XV.) is one of the most interesting in the section. 

 We have, first, the usual succession of miderclay, coal, and shale, 

 capped by a thick deposit of sandstone and shale, with erect Cala- 

 mites in the lower part, and above these prostrate trunks of Sigillaria 

 and other trees. On this rests an underclay, with a coal 6 inches 

 thick. In a bed of argillaceous sandstone, 9 feet in thickness, which 

 covers this coal, were observed four erect trees, erect Calamites, and 

 Stigtnaria, at three levels ; and in one of the erect trees (fig. 2) occurred 

 the remains of two reptilian animals, and a laud-shell described in a 

 former communication*. Only three erect trees were observed in this 

 bed in 1852t. The fourth, which I found in the summer of 1853, 

 stands on the surface of the coal, and consists merely of the coaly 

 bark enclosing a mass of fragments of decayed wood in the state of 

 mineral charcoal, as represented in figs. 14a, ms. and 146, ms. (fig. 18). 



* Quart. Jouru. Geol. Soc. May 1853, vol. ix. p. .58. 

 t One of these trees has Stigmaria-roots : fig. 8 ms. 



