From specimens kindly presented to me by Prof. Renault, I have been able to ascertain that the stems of some at least of these plants (Eucordaites) are distinct in structure from all the species of _Dadoxylon_, above mentioned, except _D. Clarkii_, of the Erian. They may be regarded as intermediate between those of conifers and cycads, which is indeed the probable position of these remarkable plants. Grand d'Eury has divided the _Cordaites_ into sub-genera, as follows: 1. _Eucordaites._--Leaves spatulate, obovate, elliptical, or lanceolate, sessile, entire, with rounded apices and of leathery consistency. The leaves are from twenty to ninety centimetres in length. The nerves are either equally or unequally strong. 2. _Dorycordaites._--Leaves lanceolate, with sharp points; nerves numerous, fine, and equal in strength. The leaves attain a length of from forty to fifty centimetres. 3. _Poacordaites._--Leaves narrow, linear, entire, blunt at the point, with nerves nearly equally strong. The leaves are as much as forty centimetres in length. To these Renault and Zeiller have added a fourth group, _Scutocordaites_. _Genus_ Sternbergia. This is merely a provisional genus intended to receive casts of the pith cylinders of various fossil trees. Their special peculiarity is that, as in the modern _Cecropia peltata_, and some species of _Ficus_, the pith consists of transverse dense partitions which, on the elongation of the internodes, become separated from each other, so as to produce a chambered pith cavity, the cast of which shows transverse furrows. The young twigs of the modern _Abies balsamifera_ present a similar structure on a minute scale. I have ascertained and described such pith-cylinders in large stems of _Dadoxylon Ouangondianum_, and _D. materiarium_. They occur also in the stems of _Cordaites_ and probably of _Sigillariæ_. I have discussed these curious fossils at length in "Acadian Geology" and in the "Journal of the Geological Society of London," 1860. The following summary is from the last-mentioned paper: _a._ As Prof. Williamson and the writer have shown, many of the _Sternbergia_ piths belong to coniferous trees of the genus _Dadoxylon_. _b._ A few specimens present multiporous tissue, of the type of _Dictyoxylon_, a plant of unknown affinities, and which, according to Williamson, has a _Sternbergia_ pith. _c._ Other examples show a true scalariform tissue, comparable with that of _Lepidodendron_ or _Sigillaria_, but of finer texture. Corda has shown that plants of the type of the former genus (his _Lomatophloios_) had _Sternbergia_ piths. Some plants of this group are by external characters loosely reckoned by botanists as ribless _Sigillariæ_ (_Clathraria_); but I believe that they are not related even ordinally to that genus. _d._ Many Carboniferous _Sternbergiæ_ show structures identical with those described above as occurring in _Cordaites_, and also in some of the trees ordinarily reckoned as _Sigillariæ_.