tracheids are especially abundant on the flanks of the conducting tracheids (figs. 431, _t_; 432, A, _t_), but they sometimes form a complete investment. In the obliquely cut vein reproduced in fig. 431, D, the transfusion-tracheids are abundant: a few are enlarged in fig. 431, E. In the smaller veins (fig. 431, A, B) they are represented by the larger elements, _t_, on the sides of the conducting strands. The protoxylem lies close to the upper edge in the middle line (_px_, figs. 431, A; 432, A); it is difficult to determine its precise position, but it would seem to be slightly internal, the bundle being not quite endarch. No phloem was recognised in the British Museum specimen, but it presumably occurred, if present, where the black patch is shown in fig. 432, A. Renault describes some phloem in sections which he examined. [Illustration: Fig. 431. _Dolerophyllum Goepperti_. Transverse sections of leaves. _e_, epidermis; _s_, secretory cells; _t_, transfusion-tracheids; _px_, protoxylem. (British Museum.)] The mesophyll next the upper surface is in most cases represented by spaces between the veins which give a crenulated outline to the parenchyma (fig. 430, C, D); in some places the spaces contain remains of very loose and crowded cells suggesting the original presence of very lacunar tissue or possibly of thin-walled storage-cells. The confinement of stomata to what is assumed to be the upper surface may, as Renault and others have suggested, indicate leaves which floated on water, an inference opposed to the view that the gaps in the mesophyll mark the position of water-tissue.