of Lepidostrobus Brownii , Schpr . 345 
stele constantly present, though it may be only comparatively 
narrow. The leaf-trace bundles of this species show an 
interesting relation to that middle delicate band of cortex 
which is so often found more or less disorganized-— it was, 
in fact, a tissue of a very spongy character, with large inter- 
cellular spaces, which were traversed by trabeculae consisting 
of one or more cell-rows. This is clearly shown in Fig. 12, 
which represents one of the leaf-trace bundles traversing 
the middle cortex of a lateral branch. The bundle (vb), 
which is badly preserved, was surrounded by a firmer band 
of cortex of some three or four layers thickness ; but further 
from the bundle the spongy tissue is readily seen, consisting 
of very irregular trabeculae with large intercellular spaces. 
It is not to be wondered at that such a tissue should 
frequently be very ill-preserved, or even disappear altogether. 
Other species also show a firmer band of cortex, internal 
to the soft middle band : thus in sections of the Laggan Bay 
Lepidodendron it is present, though only as a narrow band. 
In a section of a young twig of Lep . Spencer i also the three 
bands are seen clearly, while the middle band has a fila- 
mentous or trabecular character. But though those three 
zones of the cortex may be distinguished in some stems 
of Lepidodendron it must not be assumed that they are 
constant in all ; thus in Lep . Harcourtii , as represented by 
Williamson 1 , either the innermost firm band has never been 
present, or it has been disorganized ; the latter is hardly 
probable where more delicate structures have been, at least 
in part, preserved. Though the greater part of the cortex 
up to the central stele was probably of a delicate texture 
in L. Harcourtii , as also in the above cases, there is no 
evidence of a trabecular structure such as that described 
for Lepidostrobus Brownii ; my own specimen of Lep . 
Harcourtii , though imperfectly preserved, supports Prof. 
Williamson’s observations. In other species ( Lep . fuligi- 
nosum ), in which the preservation is very perfect, the inner 
1 Phil. Trans. 1893, B. PI. I, Figs. 1, 2, 3. 
