Fig. 325.
Saurichthys apicalis. Tooth; nat. size, and magnified. Axmouth.
Fig. 326.
Gyrolepis tenuistriatus. Scale; nat. size, and magnified. Axmouth.
The strata of red and green marl, which follow the bone-bed in the descending order at Axmouth and Aust, are destitute of organic remains; as is the case, for the most part, in the corresponding beds in almost every part of England. But fossils have lately been found at a few localities in sandstones of this formation, in Worcestershire and Warwickshire, and among them the bivalve shell called Posidonia minuta, Goldf., before mentioned ([fig. 321.] [p. 288.]).
The upper member of the English "New Red" containing this shell, in those parts of England, is, according to Messrs. Murchison and Strickland, 600 feet thick, and consists chiefly of red marl or slate, with a band of sandstone. Spines of Hybodus, called ichthyodorulites, teeth of fishes, and footprints of reptiles, with remains of a saurian called Rhyncosaurus, were observed by the same geologists in these strata.[290-A]
In Cheshire and Lancashire the gypseous and saliferous red shales and loams of the Trias are between 1000 and 1500 feet thick. In some places lenticular masses of rock-salt are interpolated between the argillaceous beds, the origin of which will be spoken of in the sequel.