ON LEPIDOPHLOIOS SCOTTII. 449 



leaf-bases continued their growth after the foliage had decayed, and that the growth 

 was longer continued on the upper side. In all the specimens of Lepidophloios Scottii 

 the leaf-bases hang downwards, and seem to have reached the limit of their growth 



(% 3). 



The leaf- trace bundles, which run from the stem through the leaf -bases to the leaves, 

 arise from the outer surface of the stele. Their xylem is derived from the protoxylem 

 of the stele, and though their direct passage into the protoxylem cannot be traced 

 accurately, it can be inferred. These xylem strands of the leaf-traces contain more 

 tracheides than each individual blunt protoxylem tooth, and are situated between two 

 adjacent protoxylems ; they are probably the result of the anastomosing of parts of the 

 protoxylem teeth between which they occur. The number of tracheides to each leaf- 

 trace varies from 15 to 25, and the whole xylem strand is elongated tangentially with 

 the smaller elements in the centre, i.e. the xylem is mesarch. The bundle has rather a 

 steep course at first, but passes out almost horizontally through the outer cortex. By 

 examining successive sections it is found that the xylem does not change in shape, and, 

 even in the leaf- base, the trace retains the same form. Before passing into the periderm, 

 however, the xylem becomes augmented by transfusion tissue, which appears to be added 

 chiefly on the lower side of the xylem. 



The phloem has mostly disappeared from the traces except in the regions of the 

 outer cortex and the leaf-bases. In the periderm zone it is seen at its best, though even 

 there it cannot be distinguished with certainty. It consists of slightly elongated, soft- 

 walled tissue, but the state of preservation does not warrant further description. Pass- 

 ing out from the periderm, the bundle is accompanied by a pariclmos strand, while 

 round it in the leaf-base are spiral cells of the mesophyll, similar to those described in 

 Williamson's XIX Memoir, and representing transfusion tissue. The leaf- trace passes 

 out of the leaf-base a little below the centre of the leaf-scar, and beyond that cannot be 

 followed, as the foliage has all decayed in the specimens examined. 



The leaf-base is of considerable size, measuring 6x6x3 mm., and is composed of 

 large-celled parenchyma. It is elongated horizontally, as the measurements indicate, 

 and is rhomboidal in section (fig. 9). The leaf-scar is about 17 mm. high (figs. 10 and 

 14, Ls.), and considerably broader, though the exact width of the scar has not been fully 

 ascertained. The leaf-base assumes its greatest width about halfway between the leaf- 

 scar and its attachment to the stem, tapering slightly in both directions. The amount 

 of tapering is not great, but is quite distinct. Near the leaf-scar, and especially round 

 the vascular bundle where it emerges on the scar, the large-celled parenchyma of the 

 leaf-base gives place to a smaller-celled and more closely packed parenchyma 

 (figs. 10 and 14). 



Within the leaf-base is the ligule pit, a bottle-shaped cavity, much elongated, and 

 lined by a layer of pallisade-like cells. This pit is placed immediately above the 

 vascular bundle of the leaf-base, and, while long cells fill in the space between the bundle 

 and the base of the ligule pit, no tracheides were observed among them. The ligule 



