t 
294 PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
new vessels in the open space between them, thus obviously being instrumental in 
repairing the breach in the continuity of the cylinder and closing it up by a succession 
of exogenous additions. It has not completely effected this object in the specimen 
under consideration, but apparently would have done so in the course of time had the 
plant survived sufficiently long for the purpose. Another remarkable circumstance 
appears in the fact that the two ligneous axes, though growing within the same stem, 
are not growing in equal ratios. Thus that to the lower part of Plate XLIII. fig. 20 is 
invested by the new layer just described, showing that in it an additional growth was 
progressing through the agency of some representative of a cambium-layer ; but in the 
twin axis above no such addition is in progress. I presume we can only infer from this 
fact that at the particular moment when the living plant was destroyed the former 
branch was pushing forward in a more active manner than the latter one — a condition 
common enough amongst recent plants, in which one Lycopodiaceous shoot takes the 
lead, whilst others are comparatively quiescent. 
At the outset of my study of the Burntisland beds my attention was arrested by the 
prevalence, in every fragment of the stratum, of broken-up cellular sporangia, indicating 
the former existence of very numerous spore-bearing fruits ; I also met with immense 
numbers of the remarkable bodies represented in Plate XLIV. fig. 27, and which 
appeared to me to be caudate macropores. The abundance of these two objects led 
me, on visting Burntisland, under the guidance of Mr. Grieve, to make special search 
for Lepidostrobi , which we soon succeeded in discovering, and at a more recent period 
Mr. Grieve has forwarded me additional specimens. They are all of one species, which 
fact is important, since it leaves little, if any, room for doubting that they belong to the 
same Lepidodendroid plant as that whose stems and branches constitute the great mass 
of the deposit. 
The general aspect of longitudinal sections of these strobili is that common to Lepi- 
dostrobi. They usually have a diameter of from less than half an inch to nearly an inch ; 
each sporangium extends from the central axis to the periphery, exhibiting in the longi- 
tudinal sections the form, so prevalent amongst these fruits, of an oblong parallelogram. 
In one of these sections now before me I count sixteen vertically disposed sporangia in 
an inch of the length of the Lepidostrobus. These dimensions approximate closely to 
those of tire beautiful cone from Burdiehouse figured by Mr. Binney*. Plate XLIV. 
fig. 23 represents a transverse section of one of these cones. The central axis (s) in this 
specimen is imperfect, its central vascular bundles having partly disappeared ; but there 
remains a thick and well-defined cortical layer composed of elongated forms of parenchyma 
approaching the prosenchymatous type, and identical with what we find in the external 
portions of some of the Lepidodendroid leaves. From this central axis are given off thick 
and robust cylindrical scales or bracts (t), consisting of a similar tissue to that of the 
cortex ; they spring from the central axis in the usual spiral order common amongst the 
* “ Observations on the Structure of Fossil Plants found in the Carboniferous Strata. — Part 2. Lepidostrobus 
and sonic allied Cones,” by E. V. Binney, F.R.S., F.G.S. (Palseontographical Society, 1871), pi. x. fig. 26. 
