This species was founded on ‘a fossil giant of the vegetable kingdom’ discovered at Wideopen near Newcastle in Carboniferous strata on the estate of Mr Brandling. The stem, 72 ft long and far from complete, showed an irregular and not a whorled distribution of branch-scars. It is noteworthy that in _D. medullaris_ (Goepp.)[672], a Permian species from Saxony, the branch-scars, while for the most part irregularly scattered, in one case showed an approach to a whorled disposition as in recent Araucarias. Witham[673] gave a fuller account of the structure of the stem than is included in the original description, and the species has been described by many later authors from both Permian and Carboniferous localities. The pith is discoid and the broad transitional region at the inner edge of the wood is a characteristic feature[674]. Thomson[675] points out that there is a tendency to a retention of the scalariform type of pitting in the region of the medullary rays. There are 1–5 rows of pits on the radial walls of the tracheids. The rays may reach a depth of 40 cells; they are usually one cell broad. It has recently been shown that as many as six vascular strands[676] may form one leaf-trace instead of the customary pair, a feature suggesting comparison with _Metacordaites Rigolloti_ Ren. with its five foliar bundles. Other species agree very closely with _D. Brandlingii_ and it is impossible to determine with accuracy the precise specific limits of stems agreeing generally with this type; but for the sake of emphasising the variation in anatomical structure it is worth while to draw attention to a few more or less divergent forms from different geographical areas. _Dadoxylon protopityoides_ Felix. An interesting feature in this Westphalian type from Germany is the occurrence of transversely elongated pits on the tracheids[677] associated with those of normal form closely simulating the pits in the xylem elements of _Protopitys_. _Dadoxylon nummularium_ White. In this Brazilian wood[678] from Permo-Carboniferous beds the medullary rays are very numerous, mostly uniseriate and 1–30 cells in depth. The pits on the tracheids are in 1–2 rows and are often contiguous. In another type, _D. meridionale_, described by the same author[679], the pits are strictly uniseriate and generally contiguous. As White says, the absence of the pith and cortex and of any evidence as to the structure of the primary xylem renders impossible any definite expression of opinion as to the affinity of these and many other species. _Dadoxylon Nicoli_ Seward.