OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 
341 
the fine sections 52 to 57. The vascular axis has been enclosed in a thick cortical 
layer. The innermost portion of this bark doubtless consisted of a delicate parenchyma, 
which has disappeared, but there remains a thick middle and outer portion, b, the 
former being composed of a less dense tissue than the latter which consists of oblong, 
more or less prosencliymatous cells, fig. 56b. From this cortical axis there spring 
numerous sporangiophores, c, arranged in the spiral order common to the Lepidodendroid 
stems. This is well shown in the tangential section, fig. 54, where then bases are seen 
at c, whilst at c their narrower cylindrical portions are divided transversely. The 
centres of these latter have evidently been occupied by prolongations of the delicate 
parenchyma of the inner bark, but which, like that tissue, have disappeared. In some 
of the sporangiophores we find the vascular bundle which also connected them with the 
main vascular axis. At their outer extremities these sporangiophores expand into 
peltate disks, 54, 55, and 56 c". * The section, fig. 53, appears to have been made 
near one extremity of the strobilus where some of these disks, seen at the right hand 
part of the figure, are in close contact with each other (53, c), and in some cases these 
sporangiophores are actually confluent (53, c'"). Fig. 55 demonstrates that each 
sporangiophore supported one sporangium, d, on its upper surface, the two having 
apparently been attached to each other about midway between the base and the peltate 
extremity of the sporangiophore ; the walls of the sporangia are composed of a single 
layer of cells (fig. 57, d), which are always somewhat oblong and frequently prosencliy- 
matous (fig. 38). 
But it is in the interior of the sporangia that the chief interest of this fruit resides. 
Lepidostrobi containing spores have been frequently described, but this is the first 
instance I have met with in which the mother cells of the spores with their numerous 
sister cells, are preserved with such remarkable definiteness. 
The sporangia, as already observed, are composed of a single layer of very strong 
prosencliymatous cells (fig. 38) like those composing the outer cortical tissue of 
the axis and its branches, though of smaller size. They differ in this respect from 
those of the Burntisland Lepidostrobus , described in my third memoir, in which the 
sporangium-wall consisted of at least a double row of parenchymatous cells arranged 
vertically to the surface of the sporangium. Within the sporangia are clustered a 
number of remarkable objects, some of which are represented in the series of figures 
from 39 to 47. 
One of the common forms of these objects is shown in fig. 39, where we have a 
central cell, a, containing a protoplasmic (?) mass, c, and with a curious oblong 
appendage, d, d, at each end, which appendages we shall find to be two sections of a 
remarkable cell. In fig. 40, we have a similar cell, but in these we find, that in 
addition to the outer cell- wall, a, there is a second inner one, b, and a third, c, which 
latter has, I presume, been the outer layer of the protoplasm or primordial utricle. 
* In the latter figure two sporangia appear vertically between the two sporangiophores, but the lower 
one, cl', is merely a portion of the wall of a sporangium belonging to the next lateral series. 
