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.)