mains of the fishes which have been so long well known, and fragments of plants, a few of which are new to England, though most of them have been described from the Kupferschiefer of Germany. The Mollusca observed by Mr. Duff consist of fragments of Nautilus Freieslebeni, Schloth., specimens of Discina nitida, Phil., Lingula mytiloides, Sow., and Myalina Hausmanni, Goldf. Of these shells, only a few imperfect specimens occurred. The appearances presented by the whole of the fossils entombed in this Marl-slate seem to lead to the conclusion that this deposit was formed in a very quiet estuary, into which the land reptiles and the freshwater Ganoids and the remains of coniferous plants were brought, to be intermixed with other exuviae, such as the shells of Nautili, Discinoe, and Linguloe, which are undoubtedly of marine origin.
The Marl-slate at this spot appears to be perfectly unconformable to the Coal-measures No. 1 of the above section. But between it and this sandstone there is an accumulation of yellow unctuous clay, about 2 feet thick, which has not the appearance of an original deposit, but appears to have been formed partly by the destruction of the lower part of the Marl-slate, and partly by the infiltration of water carrying in clayey particles through the extensive fissures which abound in the superincumbent limestone. Upwards the Marl- slate gradually passes, becoming more calcareous according to its height, into the thin-bedded compact limestone No. 3 of Prof. Sedgwick's section. It is in these transition beds, at about 7 feet above the Marl-slate proper, that our new Labyrinthodont was found. The beds of this portion are much thicker than in the compact limestone above, and more marly, and contain here and there small accumulations of gritty materials surrounded by hard compact limestone. The amphibian itself seems to have been imbedded in a very compact nodulous mass of one of these beds, and was fortunately brought to light by the splitting of the stone right through the central portion of the bed. In this part of the series at this quarry the only other fossil remains found were a few Linguloe and fragments of a Polyzoan ; but in a neighbouring quarry the beds on this horizon contain numerous remains of the well-known Permian mollusca. Although found in this higher portion of the series, we imagine there will be no difficulty in inferring that the remains of this creature were carried from its freshwater haunts to be imbedded in a deposit which was fast putting on a marine aspect.
The specimen of this new and interesting form (Pl. XXXVIII. fig. 1), for which we propose the name of Lepidotosaurus Duffii, is unfortunately in a bad state of preservation, owing partly to the crystalline condition of the matrix, and partly to the peculiar state of the bones, some of which look as if they were composed of dark grey carbonate of lime, while certain parts of them have a burnt appearance, and are reduced to a brittle, white, flaky, chalk-like substance, conspicuously displaying the concentric layers of growth. The fossil lies on its side, and is seen in vertical section, part of the bones being on one slab and part on the counter slab. The backbone (a, a, a') is split open longitudinally, there having been a natural division through this
