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It may be questioned whether some of those fossils which have the most Triassic character may not have been derived from the destruction of older strata, since in bone-beds, in general, many of the organic remains are undoubtedly derivative. Microlestes antiquus, Plieninger. Molar tooth, magnified. Upper Trias. Diegerloch, near Stuttgart, Wurtemberg. a. View of inner side? b. Same, outer side? c.
As usual in bone-beds, the teeth and bones are, for the most part, fragmentary and rolled. Orthis elegantula, Dalm. Var. Orbicularis, Sowerby. Rhynchonella navicula, Sowerby.
In Wurtemberg there are two bone-beds, namely, that containing the Microlestes, which has just been described, which constitutes, as we have seen, the uppermost member of the Trias, and another of still greater extent, and still more rich in the remains of fish and reptiles, which is of older date, intervening between the Keuper and Muschelkalk.
Similar bone-beds occur in the Carboniferous Limestone of Armagh, in Ireland, where they are made up chiefly of the teeth of fishes of the Placoid order, nearly all of them rolled as if drifted from a distance. There are upward of seventy other species of fossil fish known in the Mountain Limestone of the British Islands.
The genera Saurichthys, Hybodus, and Gyrolepis are found in both these breccias, and one of the species, Saurichthys Mongeoti, is common to both bone-beds, as is also a remarkable reptile called Nothosaurus mirabilis. The saurian called Belodon by H. von Meyer, of the Thecodont family, is another Triassic form, associated at Diegerloch with Microlestes.
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