Renault instituted this genus for petrified stems from the Permo-Carboniferous beds of Autun. _Grammatopteris Rigolloti_[1115], the type-species, is represented by a fragment, 12–15 mm. in diameter, surrounded by crowded petioles characterised by a vascular strand in the form of a short and comparatively broad plate with the smallest tracheae at each end. The solid xylem of the stem stele (protostele) has peripheral groups of protoxylem. Nothing is known as to the form of the leaves, but sporangia similar to those of _Etapteris_ (_Zygopteris_) were found in association with the stem. It is possible, as P. Bertrand suggests, that Renault’s species may be the stem of a _Tubicaulis_. _Tubicaulis._ _Tubicaulis solenites_ (Sprengel)[1116]. Fig. 304. This species from the Lower Permian of Saxony has been fully described by Stenzel[1117]. It is characterised by a very slender erect stem bearing numerous spirally disposed leaves associated with adventitious roots; the single stele (protostele) consists exclusively of tracheae, described as intermediate between the scalariform and reticulate type, surrounded by phloem. Leaf-traces are given off from the periphery of the stele where groups of smaller elements occur; these have the form of a wide-open =U=-shaped strand with the base of the =U= facing the axis of the stem. As the trace passes out towards the leaves, the ends of the =U= become more or less incurved. The stem is said to reach a metre in length and to bear compound fronds a metre long. The orientation of the leaf-trace with its concavity turned outwards is in striking contrast to the relation between leaf-trace and stem in recent ferns. [Illustration: FIG. 304. _Tubicaulis solenites._ (From Tansley, after Stenzel.) Stem and petioles: the latter numbered in the order of their age.] _Tubicaulis Sutcliffii_, Stopes[1118]. In this species the vascular axis, 2 mm. in diameter, is almost cylindrical and of the protostelic type with the protoxylem “near to or at the edge”: the tracheae are scalariform or reticulate. The leaf-traces, when first separated from the edge of the stele, are oval and gradually assume the curved form seen in _T. solenites_ (fig. 304) with the convex side towards the axis of the stem. The transition from the scalariform to the reticulate type of pitting on the tracheal walls referred to by Miss Stopes has also been noticed in some recent ferns (e.g. _Helminthostachys_) and in _Sigillaria_ (fig. 200, C, p. 212). The fact that the scalariform type of pitting is practically universal in the xylem of recent ferns, would seem to show that this character has been acquired in the course of evolution and retained in preference to the reticulate form characteristic of several Palaeozoic species. The distinction between the two methods of pitting is one of little phylogenetic importance. _Botryopteris._