BRANCH OF LEPIDOPHLOIOS FULIGINOSUS. 231 
sheath forms around the stelar branch, which at a little distance from the main stele 
becomes clothed on the inside, too, with a layer of phloem-cells. At first the branch is 
destitute of pith, but a little way from the main stele a more or less definite medullary 
tissue of parenchymatous nature can be observed both in the radial longitudinal sections 
through the tubercle and also in transverse sections of it (tangential to the main axis). 
In sections of this latter kind, the appearance of the stelar branch is very much like that 
figured by Williamson (1881) (fig. 12, pl. 51). 
The arrangement of the xylem around the pith (Pl. 25. fig. 19) is more or less radial, 
but has not the definite character of the stele in the pedunele of Cheirostrobus, Spencerites, 
or Lepidostrobus as described by Scott (1897 & 1898), Bower (1893), and Maslen (1899). 
Outside the xylem we find a dark layer of small parenchymatous cells in which 
numerous leaf-traces are embedded. Then comes a very definite band of more lightly- 
coloured cells, rectangular in shape, with their long axis in a radial direction. This 
layer of cells is exactly similar to that found within the phloem of the main axis, where 
it apparently separates the phloem from the cambium. 
Beyond this very definite layer of cells lie groups of phloem interrupted by leaf-trace 
bundles showing a very clear mesarch arrangement of their xylems (Pl. 26. fig. 18). As 
these leaf-traces pass outwards through the phloem, they carry with them some of the 
phloem-tissue, which generally appears considerably compressed. The phloem groups, 
however, which alternate with the xylem often show their structure very clearly, though 
some groups are more or less disorganized. Those which are best preserved exhibit in 
transverse section a number of large and clear polygonal cells, between which are here 
and there smaller and darker cells. Their appearance is therefore not unlike that of the 
phloem of recent Lycopodiales. In longitudinal section, however, where they can be 
easily recognized by their position and their size, the phloem-cells will be found to be 
short and rectangular, their length being about the same as that of the cells of the cortical 
sheath immediately outside. ‘The width of the phloem-cells, however, is greater than 
that of the cortical cells. In longitudinal section these phloem-cells differ considerably 
from the phloem of recent Lycopodiales, except possibly Jsoétes, and they differ also from 
the phloem-cells described by Maslen (1899) in Lepidostrobus. In none of the groups of 
phloem in the stelar branch could I find any of those divisions which are found in the 
phloem-cells of the main axis (see fig. 9, Pl. 26). But I have pointed out, in connection 
with the phloem of Zepidophloios (1901), that in the leaf-trace bundles, too, there is an 
absence of these longitudinal divisions of the phloem-cells. 
The stelar branch, on its way to the tubercle, is always surrounded by a sheath of dense 
cells continuous with the inner cortex which surrounds the main stele, and from its very 
commencement it gives off leaf-traces which can be seen cut transversely in this inner 
cortical sheath. Even when these leaf-traces pass out into the mid-cortex, they remain 
much more parallel to the stelar branch than is the case with the leaf-traces given off 
from the main stele. 
In passing into the outer cortex, the stelar branch retains a fairly thick sheath of tissue 
continuous with the middle cortex, which can be seen in the transverse section of the 
stem (Pl. 26. fig. 16) and also in a section passing transversely through the base of the 
