500 
PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
Halifax beds, associated with a still greater profusion of microspores, which latter I 
concluded belonged to the same S23ecies of strobilus as the macrospores. Since that 
memoir was written we have found the strobilus in a section made for me by 
Mr. Earnshaw, of Oldham. We had looked for a strobilus of considerable size, like 
those common hr the carboniferous strata, whereas it is remarkable for its small 
dimensions ; but that it has been fully grown is shown by the perfect development of 
its macrospores. The specimen is much crushed, as is seen in fig. 8, which represents 
it enlarged nearly 12 diameters. At a we find the usual central vasculo-cellular axis. 
At b, b are clusters of macrospores, several of them being enclosed in their sporangial 
envelopes. The upper part of the strobilus, c, has been cut off obliquely, owing to 
some accidental curvature in its form ; but the entire absence of macrospores from the 
portion of it which remains shows the distinctiveness of its character from the lower 
macrospore-bearing part. At d we have two sporangia full of microspores, possibly 
disturbed by the pressure from their original positions.* The surrounding matrix is 
full of microspores. The entire length of this section is '33. The strobilus was doubt¬ 
less a little longer when perfect at its upper extremity ; but when every allowance is 
made for the missing portion it remains a diminutive organism, reminding us more of 
the dwarfed fruits of many living Selaginellce than of the larger Lepidostrobi winch 
are so abundant in the upper Coal-measures. 
In Plate 23, figs. 64 and 64*, of my last memoir I figured some anomalous pedun¬ 
cular organs connected with the macrospores of this strobilus, which were wholly 
inexplicable to me when that memoir was written. Further research has cleared up 
the mystery. Fig. 9 represents a cluster of four macrospores, which demonstrate that 
these pedunculate appendages are but collapsed portions of the spore-wall, due pro¬ 
bably to the destruction of their contained protoplasm, and consequent arrested 
growth. This is especially obvious in the two macrospores, a and b. Fig. 10 repre¬ 
sents a tangential section of a detached bract of a different Lepidostrobus, with its 
sporangium on its upper surface filled with microspores. The slightly-distorted bract 
is seen at a, composed of strongly-defined cells at its upper portion, cc, and of a more 
delicate parenchyma interiorly. In this strongly-marked differentiation of the upper 
and lower tissues of the bract the strobilus differs from the Burntisland one.t The 
structure of the sporangium-wall, b, is identical with that of the similar one surround¬ 
ing the macrospores. + The mode of attachment of this cellular investment to the 
* At the same time it must not be forgotten that whilst in the greater number of the Lycopodiaeece 
the macrospores occupy the lower extremity of the strobilus, and the microspores its apical portion, there 
are several, such as SelagineUa Martensii, in which the macro- and micro-sporangia are intermingled 
without any regularity in their arrangement. I have found this to be partially the case with the Lepido¬ 
strobus from Burntisland. In the macrospores of S. Martensii the exosporium is furnished with long 
radiating spines, which, as Burmeister has shown, become brittle and are often broken off. I have fre¬ 
quently found the similar appendages of the Halifax macrospores broken into detached fragments. 
t Memoir, Part III., Plate 44, fig. 25. 
1 Memoir, Part IX., Plate 23, fig. 64. 
