347 
of Lepidostrobus Brownii , Sckpr. 
appear in the middle cortex. Such mucilaginous cavities are, 
however, a marked feature in the cortex of L . inundatum , 
while large intercellular spaces are found in the middle cortex 
of that species, and are traversed by plates of cells or trabe- 
culae (Fig. 14); but beyond this the cortex of Z. inundatum 
is not clearly differentiated. In the more common British 
species, however, the cortex is differentiated into distinct 
bands. L. clavatitm shows a very dense and hard inner 
cortex, and a similar, though often narrower, dense band at the 
periphery, while between there is a lax thin- walled tissue, 
which is very readily broken down ; the size of the inter- 
cellular spaces in this tissue is variable. Such characters are 
found both in the creeping vegetative stem and in the axes 
which bear the strobilus. In L. alpinurn , in both vegetative 
and strobiloid axes, the inner cortex appears as a dense band ; 
it merges gradually into a lax lacunar tissue, in which the 
cells are elongated into filamentous trabeculae very irregularly 
disposed. This spongy mass extends to the peripheral epi- 
dermis, so that the outer firm band of cortex is entirely 
unrepresented in this species (Fig. 1 5) ; this spongy tissue is 
very similar to the mesophyll of the leaves of the same plant, 
and the leaf-cushions may thus be described as extending 
over the surface of the axis. 
In Z. Selago there is a narrow band of inner cortex, not 
clearly marked, surrounding the stele, a broad band of thinner 
walled and more lax middle cortex, and an outer firmer band ; 
but none of these are clearly defined, nor are the cell-walls 
lignified excepting the outer band, and that only at a com- 
paratively late stage. The chief interest in the cortex of this 
plant lies in the middle band ; for there, in old stems, the 
tissue shows that peculiar appearance of interlaced filaments 
which has been alluded to as existing in Lep. fuliginosum 
(Fig. 13). In L. Selago the peculiarity is shown in a less 
degree, but it is quite similar in kind. Lastly, in L. nummu- 
lar folium, Blume, the cortex shows the converse of what is 
seen in L. alpinurn, the peripheral part being dense, with 
thickened walls, while the inner tissues are relatively thin- 
