The aerial shoots of this species are occasionally branched dichotomously[539], the apical portions bearing short crowded leaves[540]; the surface of the bark is either completely covered with contiguous leaf-scars without definite leaf-cushions or with projecting cushions forming a narrow sloping surface surrounding each leaf-scar. Other parts of the plant may possess cushions similar in their kite-shaped form to those of _Lepidodendron_, but without a median vertical groove, or the leaf-scars may be spirally disposed at varying distances apart on a comparatively smooth and longitudinally wrinkled bark. The species exhibits striking instances of a transition between the Favularian, Clathrarian, and Leiodermarian forms of stems. The leaf-scars, which are hexagonal in outline,—the lateral angles pointed and transversely elongated, the upper and lower angles rounded,—bear three scars, the central leaf-trace and two straight or curved lateral parichnos scars; a ligular pit occurs immediately above the centre of the upper edge of the leaf-scar and occasionally circular elevations with a central pit occur singly or in pairs below a leaf-scar (fig. 196, A). The linear leaves, which may persist on shoots having a fairly large diameter[541], have a single median vein and two stomatal grooves on the lower surface[542] (fig. 200, D). Partially decorticated and younger shoots are characterised by the occurrence of pairs of elliptical parichnos areas and a smaller median leaf-trace scar. The surface of older stems, which may show signs of longitudinal splitting (_Syringodendron_ state), bears pairs of parichnos scars reaching a length of 2–2·5 cm. and a breadth of 10–13 mm. The regularity of the leaf-scar arrangement is interrupted at intervals by the occurrence of more or less regular verticils of scars marking the position of deciduous shoots. Grand’Eury[543] has figured cones which he believes to be those of this species, and Zeiller refers the large strobili, _Sigillariostrobus major_, to _Sigillaria Brardi_[544]. The subterranean axes were characterised by spirally disposed rootlet-scars like those of _Stigmaria ficoides_ (figs. 204, 205) and by a cortical surface with the features of _Stigmaria rimosa_ Gold.[545] The anatomy of the stele and leaves has already been described (p. 219). The stele of the Stigmarian portion of the plant consists of a band of centripetal primary xylem and a cylinder of centrifugally formed secondary wood with medullary rays containing vascular bundles passing out to the rootlets[546]. _Sigillaria Brardi_ occurs not uncommonly in Permian rocks; it is recorded from France[547], Germany[548], Pennsylvania[549], and elsewhere. It is found in the Upper, Middle, and Lower Coal-Measures of England[550] and in Permo-Carboniferous strata in Africa[551] and Brazil[552]. CHAPTER XVII. UNDERGROUND RHIZOMES AND ROOTS OF PALAEOZOIC LYCOPODIACEOUS PLANTS.