This Permian species from Autun[689] differs from typical examples of the genus in the differentiation of the pith into a central thin-walled region contracted into transverse diaphragms surrounded by a cylinder of stouter tissue and in the greater breadth of the medullary rays. The tracheids have 3–4 rows of pits of the usual type. Spirally disposed, decurrent, leaf-bases occur on the surface of the stem, and the cortex includes secretory canals and strands of hypodermal stereome. A small number of veins pass up the median part of the lamina which in this respect and in its greater thickness differs from that of _Cordaites_ leaves. Renault speaks of the rays as a cycadean feature, but they are only two cells in width and shorter than in recent Cycads. _Dadoxylon spetsbergense_ Gothan. In this species[690] from Spitzbergen, of doubtful age though probably Palaeozoic, there is no xylem-parenchyma and the medullary rays are from 2 to 5 cells deep; the bordered pits occur in 1–2 or rarely 3 rows on the radial walls of the tracheids; they are alternate but not flattened and characterised by their small size (7μ high); they do not cover the whole face of the tracheids. It is pointed out that in many Palaeozoic and Mesozoic Dadoxylons the pits are larger than in recent species (16–17·5μ as compared with 9–12μ) while in _D. spetsbergense_ they are still smaller. The large size of the medullary-ray cells is another noteworthy feature, also the absence of annual rings, a character possibly connected with conditions of growth in northern regions. It is, however, pointed out by Nathorst[691] that the fossil was not found _in situ_ and, as he says, it may have been carried by currents from a more southern locality. =Metacordaites.= Renault. _Metacordaites Rigolloti_ Renault. Renault founded this species[692] and genus on a stem from Autun which, like _D. Pedroi_, differs in certain respects from stems usually attributed to _Cordaites_. The pith is solid and contains secretory ducts and cells; the tracheids have often a single row of pits, and multiseriate pitting is much less common than in _Dadoxylon_. The medullary rays are generally 1–6 cells deep. A striking feature is the occurrence of groups of five vascular bundles penetrating the secondary wood in V-shaped groups, each group being regarded as a multiple leaf-trace, a type recently recognised by Thomson in _D. Brandlingii_. In one of Renault’s figures a larger scar, presumably a branch-scar, is shown immediately above a group of foliar bundles. The genus _Metacordaites_ is considered by its author to be intermediate between Conifers and the Cordaitales, but nearer to the former. This conclusion is, however, based on insufficient evidence, as nothing is known of the reproductive organs. +Roots.+