Equisetites Muensteri is a characteristic and fairly widely spread Rhaetic and Liassic species, having a comparatively slender stem, with leaf-sheaths consisting of a few broad and short leaf-segments.
The oldest beds which have yet been recognized are shales and hornstones with Liassic fossils.
And when we know that the Chrysomelidae and Buprestidae also lived in Triassic, and the Carabidae, Elateridae, Cerambycidae and Scarabaeidae, in Liassic times, we cannot doubt that the great majority of our existing families had already been differentiated at the beginning of the Mesozoic epoch.
Ctenozamites occurs chiefly in the Rhaetic coal-bearing beds of Scania, and has been found also in the Liassic clays of FIG.
Geologically they are known to date back to the Oligocene period, and wings believed to be referable to them have been found in Liassic and Jurassic beds.
The Liassic beds are often metamorphosed and the limestones contain garnet and wollastonite.
From the Permian to the Lias the sequence in the central Himalaya shows no sign of a break, nor has any unconformity been proved between the Liassic beds and the overlying Spiti shales, which contain fossils of Middle and Upper Jurassic age.
In many of the flowers described by Mr Wieland the structure is identical in essential features with that of the female flowers of Bennettites Gibsonianus described by Carruthers and by Solms-Laubach, and with that of a French Liassic species described by Lignier: the whole consists of a convex receptacle bearing mature seeds at the tips of pedicels associated with interseminal scales (fig.
Fossil Trichoptera occur in rocks of Liassic age.
A genus Zonatrichites, compared with species of Cyanophyceae, has been described as a Calcareous alga from Liassic limestones of Silesia.