Taeniopteris jejunata, Grand’Eury[1266].
This species differs from T. multinervis in its bipinnate fronds; the linear or oval-linear pinnae are attached by a short stalk to the primary rachis and reach a length of 25 cm.; the veins are less crowded, 12–15 per centimetre.
T. jejunata is recorded from the Coal-fields of the Loire and Commentry[1267] in France, from the Lower Permian of Thuringia[1268], and elsewhere.
Taeniopteris Carnoti, Ren. and Zeiller[1269]. Fig. 330, A.
This species, founded on portions of pinnate fronds from the Coal-field of Commentry, is characterised by rather broader (25–30 mm.) pinnules, with short pedicels and a cordate base, reaching a length of 25–30 cm. The secondary forked veins are more numerous than in T. jejunata. In T. multinervis the pinnules are still broader and have a stronger midrib.
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Several species of Taeniopteris have been described from Triasso-Rhaetic rocks in Europe, India, Tonkin and elsewhere. In some cases it is practically impossible to recognise clear specific distinctions between Rhaetic and Jurassic types.
From the Damuda and Panchet series of India (Triasso-Rhaetic) Feistmantel has described large sterile fronds as Macrotaeniopteris Feddeni[1270] which reach a breadth of 20 cm.: these may be compared with the Indian species Taeniopteris lata Oldham[1271], and to T. gigantea from the Rhaetic of Franconia[1272] and Scania. A specimen of this species figured by Nathorst[1273] from Scania has a lamina 33 cm. broad. Other examples are afforded by M. Wianamattae Feist.[1274] from rocks of the same age in Australia and by Taeniopteris superba Sap.[1275] from Lower Rhaetic rocks near Autun.
From the Rhaetic of Tonkin, Zeiller records several species, among which may be mentioned T. Jourdyi Zeill.[1276] and T. spatulata MacClelland ([fig. 330], B, C). Both have simple fronds. Those of T. Jourdyi reach a length of 10–40 cm. and a breadth of 10–70 mm.; the rachis is characterised by crowded and discontinuous transverse folds, and the secondary veins (35–50 per cm.) are usually at right angles to the rachis. This Tonkin species is compared by Zeiller with the European Rhaetic species T. tenuinervis Brauns.
The polymorphism of the fronds is a striking feature: in one case described by Zeiller the lamina appears to be divided into segments like those characteristic of the leaf of the Cycadean genus Anomozamites. It is obviously difficult in many instances to distinguish between detached Taeniopteroid pinnae of a compound frond and complete simple leaves. In some compound fern fronds, as in the recent Polypodiaceous genus Didymochlaena, the pinnules are deciduous, and the same feature undoubtedly characterised the fronds of many extinct species. A specimen figured by Zeiller which shows several petioles of T. Jourdyi attached to a thick stem[1277] demonstrates the simple nature of the leaves. In other cases, e.g. T. vittata, specimens occur in which the slightly enlarged petiole-base has a clean-cut surface indicating abscission from a rhizome ([fig. 332]).