The red colour of the New Red Sandstones and marls is caused by peroxide of iron, which may also have been carried into the lakes in solution, as a carbonate, and afterwards converted into peroxide by contact with air, and precipitated as a thin pellicle upon the sedimentary grains of sandy mud, of which the Triassic beds more or less consist. Professor Ramsay further considers that all the red-coloured strata of England, including the Permian, Old Red Sandstone, and even the Old Cambrian formation, were deposited in lakes or inland waters.[55] [55] A. C. Ramsay, _Quart. Jour. Geol. Soc._, vol. 27, p. 191. * * * * * There is little to be said of the animals which belong to the Saliferous period. They are nearly the same as those of the Muschelkalk, &c. Among the most abundant of the shells belonging to the upper Trias, in all the countries where it has been examined, are the _Avicula, Cardium_, and _Pecten_, one of which is given in Fig. 85. Foraminifera are numerous in the Keuper marls. The remains of land-plants, and the peculiarities of some of the reptiles of the Keuper period, tend to confirm the opinion of Professor Ramsay, that the strata were deposited in inland salt-lakes. In the Keuper period the islands and continents presented few mountains; they were intersected here and there by large lakes, with flat and uniform banks. The vegetation on their shores was very abundant, and we possess its remains in great numbers. The Keuper Flora was very analogous to those of the Lias and Oolite, and consisted of Ferns, Equisetaceæ, Cycads, Conifers, and a few plants, which M. Ad. Brongniart classes among the dubious monocotyledons. Among the Ferns may be quoted many species of _Sphenopteris_ or _Pecopteris_. Among them, _Pecopteris Stuttgartiensis_, a tree with channelled trunk, which rises to a considerable height without throwing out branches, and terminates in a crown of leaves finely cut and with long petioles; the _Equisetites columnaris_, a great Equisetum analogous to the horse-tails of our age, but of infinitely larger dimensions, its long fluted trunk, surmounted by an elongated fructification, towering over all the other trees of the marshy soil. [Illustration: Fig. 85.--Pecten orbicularis.] The _Pterophyllum Jägeri_ and _P. Münsteri_ represented the Cycads, the _Taxodites Münsterianus_ represented the Conifers, and, finally, the trunk of the Calamites was covered with a creeping plant, having elliptical leaves, with a re-curving nervature borne upon its long petioles, and the fruit disposed in bunches; this is the _Preissleria antiqua_, a doubtful monocotyledon, according to Brongniart, but M. Unger places it in the family of _Smilax_, of which it will thus be the earliest representative. The same botanist classes with the canes a marsh-plant very common in this period, the _Palæoxyris Münsteri_, which Brongniart classes with the _Preissleria_ among his doubtful Monocotyledons.