Miss Elkins and W. Wieland[774] have recently described some Upper Devonian wood from Indiana characterised by a grouping of the circular or elliptical bordered pits in the radial walls of the tracheids similar to those in _Callixylon Trifilievi_ which they include together with the Middle Devonian species _Cordaites Newberryi_[775] in Zalessky’s genus. Though these two American species are comparable in the discontinuous arrangement of the tracheal pits with the Russian type the latter is characterised by the presence of primary xylem-strands, a feature that has not been recognised in the American stems: it would seem, then, undesirable to adopt the designation _Callixylon_ in preference to _Dadoxylon_ unless there is evidence as to similar characters in the primary region of the xylem. =Coenoxylon.= Zalessky. _Coenoxylon Scotti_ Zalessky. Prof. Zalessky[776] gave the name _Coenoxylon_ to a small and incomplete piece of stem of doubtful provenance but possibly from the Ural Permian beds. The pith, 2 cm. broad, consists of parenchyma associated in the central region with numerous large sclerous cells. In one section a sinuous band of meristematic tissue was observed near the periphery of the pith: the appearance of this tissue in a photograph given to me by Prof. Zalessky suggests comparison with occasional strips of similar dividing cells in the pith of _Lyginopteris_. The secondary wood is composed of tracheids with 1–2 rows of flattened or hexagonal pits on the radial walls and narrow uniseriate medullary rays reaching a depth of 15 cells and with 2–7 oval pits in the field. As in the wood of _Mesopitys Tchihatcheffi_[777] there are distinct and apparently complete rings of growth. It is on the ground of the arrangement and structure of the primary xylem that Zalessky instituted a new generic name. The primary xylem forms teeth of variable size which project into the pith from the edge of the secondary xylem: the prominent portions of the main mass of primary xylem give off branches, differing considerably in size and shape, some of which become separated by a comparatively broad band of parenchyma from the parent xylem-tissue. These bundles anastomose in their course through the pith and in doing so incorporate between them patches of parenchyma. The bundles of primary xylem are endarch. From the centrifugal strands at the periphery of the pith double leaf-traces are produced which pass almost horizontally through the secondary wood. As Zalessky points out, the leaf-traces in their dual nature and in the elongated and narrow form of the tracheal groups, as seen in tangential section of the secondary wood, bear a close resemblance to those of _Ginkgo biloba_. This Russian genus agrees in its double leaf-trace with _Mesoxylon_, _Mesopitys_, and _Antarcticoxylon_: among recent plants _Ginkgo_ would seem to be the most closely allied type. =Parapitys.= Zalessky.