Fig. 270.

(A, B, F, G, after Zeiller; D, after Hooker; E, after Stur.)

A fertile sphenopteroid frond figured by Schimper as Hymenophyllum Weissi[890] from the Coal-Measures of Saarbrücken bears some resemblance to recent Hymenophyllaceae, but the figures are by no means convincing: an examination of the type-specimens in the Strassburg Museum led Solms-Laubach[891] to express dissent from Schimper’s determination. A more satisfactory example is that afforded by the fertile pieces of a frond described by Zeiller[892] from French Coal-Measures as Hymenophyllites quadridactylites (Gutbier). Some of the ultimate segments with a truncated tip are preserved in close association with a group of oval sporangia with a complete transverse annulus ([fig. 270], F, G). The position of the sporangia is such as to suggest their separation from a terminal columnar receptacle like that in Trichomanes and Hymenophyllum. In his account of this species from the Coal-Measures of the Forest of Wyre, Kidston[893] states that Zeiller informed him that he had noticed traces of what appeared to be a columnar receptacle in the French specimens.

The records of Hymenophyllaceae from the Mesozoic and Tertiary formations are not such as need detain us. The facts bearing on the geological history of this family are singularly meagre. There is no evidence which can be adduced in favour of regarding the Hymenophyllaceae as ferns of great antiquity, which played a prominent part in the floras of the past.

It is interesting to find that the genus Ankyropteris[894], one of the Botryopterideae (a group of Palaeozoic Ferns for which I propose the name Coenopterideae), has a morphological character in common with Trichomanes, namely the production of axillary buds: there are also features in the stelar anatomy shared by the Botryopterideae and Hymenophyllaceae[895]. These resemblances, though by no means amounting to proof of near relationship, point to a remote ancestry for certain features retained by existing members of the Hymenophyllaceae.

Cyatheaceae.

The specimens from the Culm rocks of Moravia on which Stur founded the species Thyrsopteris schistorum[896] are too imperfectly preserved to warrant the use of this generic name. Goeppert[897] in 1836 instituted the genera Cyatheites, Hemitelites, and Balantites for species of Carboniferous ferns believed to be closely allied to recent Cyatheaceae, but a fuller knowledge of these types has clearly demonstrated that in all cases the reference to this family had no justification.

The Upper Carboniferous species Dicksonites Pluckeneti, of which Sterzel[898] described fertile specimens in 1886 as possessing circular sori, has since been shown by Grand’Eury[899] to be a Pteridosperm bearing small seeds. In Sphenopteris (Discopteris) cristata (Brongn.) Zeiller[900] has described sori very like those of Cyathea and Alsophila, but differing in the exannulate sporangia: this species, like so many of the Palaeozoic ferns, is probably more akin to the Marattiaceae than to the Cyatheaceae.