OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 
297 
retaining the bases of the petioles after the fronds have fallen ; whilst yet lower down 
on the stem these petioles have disappeared, revealing characteristic lozenge-shaped scars, 
rendered visible less by the disarticulation of the petioles than by a process of weathering 
which has disintegrated them down to the level of the cortical layer. It appears to me 
exceedingly possible that similar phenomena may have occurred in the case of the plants 
under consideration. In the few fragments of true Lepidodendroid scars which I have 
met with these scars are long and narrow, corresponding very closely with what I observe 
on some of the smaller twigs described, from which the leaves have become accidentally 
detached. These circumstances combine to remove all doubt as to the relationship 
subsisting between the stems and branches described in the earlier part of this memoir 
and the strobilus last considered : either as fragments of sporangia and detached spores 
on the one hand, or as leaves and portions of stems and branches on the other, the two 
classes of vegetative and reproductive organs are represented in every square inch of the 
rock I have examined ; and as every strobilus which I have obtained is of one species? 
and that one identical with the innumerable distinctive macrospores referred to, it appears 
to me that we have every proof of their identity that palaeontology can furnish, unless 
we could discover the tree in its integrity, which is impossible. 
I have stated that the central axes of these strobili are commonly imperfect. In one 
of them we have the usual central bundle of barred vessels partly preserved ; but I 
have obtained one larger specimen, represented in Plate XLIV. figs. 29 & 30, which I 
think may possibly belong to the same fruit. If so, it has been part of the base of 
the axis of a somewhat larger strobilus than those described. Fig. 29 represents a 
transverse section of it, in which is seen a central star-shaped cluster of barred vessels 
(.S'), surrounded by a vacant space from which delicate cellular tissue, corresponding 
with the inner or middle bark of the Lepidodendroid twigs, has doubtless disappeared. 
External to this is a thick cortical layer of parenchymatous and prosencliymatous tissue, 
the peripheral portion of which has broken up into thick divergent bracts, each of which 
has again divided into secondary ones, as described in the preceding pages. This diver- 
gence is demonstrated by the subdivisions of the vascular bundles seen at t t'. On 
turning to the longitudinal section (fig. 30) we see that the vascular bundles of the 
bracts have, as was to be expected, sprung from the central axis (s) at s ' , and after 
traversing the clear area (g) have proceeded upwards and outwards through the thick 
cortex, as shown by the numerous vacant spaces ( m ) from which the vessels have 
disappeared. Peripherally the bark breaks up into main or primary bracts, which 
again subdivide, as in the transverse section, into secondary ones, demonstrating that 
each primary bract does not merely dichotomize but subdivides, both horizontally and 
vertically, into a cluster of bracts — a condition corresponding with what I have already 
observed in the smaller strobili described. The external surface of the central vascular 
axis (,s) has evidently been deeply sulcated longitudinally, the vascular bundles having 
sprung from the intermediate ridges. In the transverse section the vessels of the outer- 
most portions of these ridges exhibit a radiating arrangement, as if the axis had made a 
