Lesleya.
This generic designation was instituted by Lesquereux[1359] for simple oval-linear leaves from the Coal-Measures of Pennsylvania. The leaves so named are probably generically identical with the specimen doubtfully assigned by Brongniart[1360] to the Coal-Measures, and made by him the type of the genus Cannophyllites on the ground of a resemblance to the leaves of the recent flowering plant Canna. Fig. 347 illustrates the form of a Lesleya leaf from the Coal-basin of Gard, named by Grand’Eury L. simplicinervis[1361], a type in which the veins are frequently unbranched and not repeatedly forked as in most examples of the genus ([fig. 329], C). The features of the genus are, the oval-linear or lanceolate shape of the presumably simple frond, its entire or, in one species at least (L. Delafondi, Zeill.), finely dentate margin, the stout rachis giving off at a very acute angle numerous dichotomously branched secondary veins. In L. Delafondi ([fig. 329], C), described by Zeiller[1362] from the Lower Permian of Autun, the frond may reach a length of more than 20 cm. and a breadth of 8 cm. Similar species are represented by L. ensis[1363] from the coal-field of Commentry, and L. grandis[1364] from Upper Carboniferous rocks of North America. The genus is characteristic of Upper Carboniferous and Lower Permian strata: the form of the leaf and the direction of the secondary veins suggest comparison with Glossopteris, but in Lesleya there are no cross-connexions between the veins. Nothing is known as to the fructification, a fact which naturally evokes the opinion that the genus is a Pteridosperm[1365] and not a true fern. Some years before the discovery of Pteridosperms, Grand’Eury[1366] suggested that Lesleya might be a Gymnosperm; his opinion being based on the woody nature of the rachis and on the simple venation of Lesleya simplicinervis.
Fig. 347. Leslya simplicinervis, Grand’Eury. (Reduced: after Grand’Eury.)
Neuropteridium.
In their monograph of fossil plants from the Bunter Series of the Vosges, Schimper and Mougeot[1367] described some pinnate leaves of ferns as species of the genus Neuropteris. In 1869 Schimper[1368] placed these in a new sub-genus Neuropteridium, in order to draw attention to the fact that their fronds appear to be simply pinnate and not bipinnate or tripinnate as in Neuropteris. The type-species of Neuropteridium is N. grandifolia Sch. and Moug. from the Bunter Sandstones of the Vosges. The genus includes Triassic European species and the widely distributed Permo-Carboniferous species from Brazil[1369] originally described by Carruthers as Odontopteris Plantiana. It is probable that some Carboniferous plants, particularly species from the lower members of the formation, referred to the genus Cardiopteris, are not genetically distinct from the Indian and southern hemisphere type Neuropteridium validum (= Odontopteris Plantiana).
Fronds pinnate, linear; a broad rachis bears pinnules which may be either semicircular or broadly linear with an entire or lobed margin. The longer pinnules may exceed 6 cm. in length. The pinnules agree with those of Neuropteris in being attached by the median portion of the lamina and not by the whole base, which is more or less auriculate. In some cases the repeatedly forked veins diverge from the centre of the pinnule base; in others there is a midrib which persists for a short distance only, and in some species the more persistent median vein gives the segments a closer resemblance to those of Neuropteris. Fructification unknown, with the exception of obscure indications of sporangia (?) on the fertile leaves of a Triassic species.
Fig. 348. Neuropteridium validum, Feist. Nat. size. From the Karharbári Coal-field, India. From Arber, after Feistmantel.