Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/381

 strata sometimes associated with bands of fossiliferous magnesian limestone. No shells of any kind have been found in the so-called Rothliegende of Lancashire, or in the Permian beds in the Vale of Eden, while plants occur in the middle division of that series, as mentioned by Professor Harkness.

The evidence derived from reptilian remains in the red beds, so far as it yet goes, is of the same kind as that afforded by the Keuper sandstones. First we have Dasyceps Bucklandi in the Permian beds near Kenilworth ; nest the footprints mentioned by Professor Harkness in the red sandstones of the Vale of Eden, as occurring at Brownrigg, in Plumpton, and near Penrith ; and lastly the numerous footprints described by Sir William Jardine, in the sandstones of Corncockle Moor and other parts of Dumfriesshire, now universally believed to be of Permian age. All of these prints indicate that the animals were accustomed to walk on bare damp surfaces, which were afterwards dried in the sun before the flooded waters overspread them with new layers of sediment, in a manner that now takes place during variations of the seasons in many salt lakes. Pseudomorphs of crystals of salt * in the Permian beds of the Vale of Eden, and deposits of gypsum and peroxide of iron, help to this conclusion, together with the occurrence of ripplings, sun-cracks, and rain-pittings impressed on the beds.

The remaining fossils that require to be considered in the red sandstones and marls belong exclusively to marine genera.

In Lancashire the Lower Permian red sandstones, which Mr. Hull estimates as about 1500 feet thick on the banks of the Mersey and Tame, are unfossiliferous, and the Upper Permian strata, consisting of red marls with bands of magnesian limestone, contain a few true Magnesian-Limestone species, viz. Gervillia antiqua, Pleurophorus costatus, Schizodus obscurus, S. rotundatus, Turbo helicinus, T. obtusa, Rissoa Leighi, R. Gibsoni, Natica minima, and some others†. They are all small and dwarfed, and in this respect and the small number of genera they resemble the living molluscan fauna of the Caspian Sea.

In the true Magnesian-Limestone districts of the east of England the case is different. There we find a more numerous marine molluscan fauna, but wonderfully restricted when compared with that of Carboniferous times. From Mr. Etheridge's unpublished lists it may be roughly estimated as follows : —

Brachiopoda. Camarophoria 3, Crania 2, Discina 1, Lingula 2, Producta 2, Spirifera 3, Spiriferina 2, Strophalosia 4, Terebratula 2 : in all, 9 genera and 21 species.

Lamellibranchiata. Aucella 1, Mytilus 2, Avicula 2, Gervillia 5, Arca 2, Cardiomorpha 1, Ctenodonta 1, Leda 1, Myalina 1, Myoconcha 1, Pleurophorus 1, Edmondia 1, Astarte 2, Schizodus 5, Solemya 4, Tellina 1 : in all, 16 genera and 31 species.

Univalves. Calyptroea 1, Chemnitzia 1, Chiton 3, Chitonellus 4,


 * Harkness, Quart. Journ. Geol. Soc. 1862, vol. xviii. p. 215.

† Taken from Mr. Hull's " Memoir on the Country around Oldham," and corrected for generic names according to Mr. Etheridge's lists.