On the Tree Ferns of the Coal-Measures, and their Relations to other Living and Fossil Forms

Abstract

After referring to the remarkably uniform character of the order of Ferns throughout their whole history on the globe, the author pointed out that there existed in the Coal-Measures two very distinct kinds of fern-stems, each represented by several species. Both of these were very different from the Chelepteris -group already described by the author in the Journal of the Society. The first group had a stem-structure like that of living tree ferns. In them the vascular elements of the stem formed a close cylinder round the pith; and the vascular bundles for the leaves were given off from the out-turned edges of the cylinder, where, at regular intervals, corresponding to the position of the leaves, narrow meshes occur for this purpose. To this group were referred the stem described by Lindley and Hutton as Caulopteris Phillipsii , and several hitherto undescribed species from Radstock and Newcastle. No materials had yet been detected which could throw any light on the foliage or fruit of these fern-stems. The second group included some stems the casts of which the author had obtained from Radstock, and the root-structures from Halifax. By the help of a fine series of specicimens in the collections of the British Museum, he was able to correlate the different parts of these plants. The stems had been described by Corda under the name of Stemmatopteris . They differed from the other group chiefly in having the ends of the vascular plates, as seen in the transverse section, turned inwards, and having the bundles of the leaves formed in a complete condition in the axis of the stem. The author showed that the relation of the different parts of the stem in the species of Caulopteris was tile same as in a first year's dicotyledon; while in the latter group the analogy of the structures was with the monocotyledonous stem. The roots, which surrounded the older portions of the stem, formed the well-known genus Psaronius , of Cotta; and as this was the earlier name, it was proposed to retain it for the genus. There was associated with all the fine specimens of this group, which the author had received from J. M'Murtrie, Esq., F.G.S., foliage which had been described as Cyatheites arborescens . Although this had not been observed organically connected with the stems, the author adduced several reasons for believing that it belonged to them. If this connexion could be established, it was of the greater importance, as this form was known in fruit; and the fruit established that its affinities were with the living Alsophilas and Cyatheas. Many species of this genus occurred in the continental coal-fields; but the author believed that all the specimens found in England, though differing considerably amongst themselves, belonged to a single species.