87 
A British Fossil Selaginella. 
or pebbled 1 outer coat which gives them a pitted appearance, the 
depressions between the short rounded tubercles givingthe impression 
of small circular pits (Figs. 4, 5). The three-rayed marking is very 
distinct on the wall of the spore reproduced in Fig. 4. The megaspores, 
0.30-0.35 mm. in diameter, are usually oval or almost spherical 
with a three-sided pyramidal apex. As seen in Fig. 6, which repre¬ 
sents the greater part of one spore with a portion of a second in 
close association, the thick wall has an irregularly reticulate surface 
precisely as in the megaspores of several recent species. 3 Fig. 7 
illustrates the difference in size between the two kinds of spore 
and shows the wall of the megaspore opening along the three-rayed 
apical ridge. In the interior of one of the megaspores a thin inner 
membrane was noticed, separated a short distance from the much 
thicker outer wall, presenting an appearance very similar to that 
in recent megaspores where the exine and intine are often widely 
separated. 3 
The very close resemblance, which it may fairly be said 
amounts to identity, between the basal narrower portion of the 
fertile fragment shown in Fig. 2 and the vegetative shoot reproduced 
in Fig. 1 leaves no doubt as to the connexion between these two 
closely associated specimens. The sterile tufted shoot (Fig. 1), 
which is undoubtedly specifically identical with that reproduced in 
the Wealden Catalogue, shows on slight magnification the impres¬ 
sions of small broadly triangular leaves, the tips of which are 
indicated at the edges of the enlarged portion shown in Fig. la. 
The preservation does not admit of any definite statement as to the 
occurrence of one or two forms of foliage-leaves. 
While it is clearly impossible to speak with confidence as to 
the precise relationship of the Wealden plant to existing species, 
there are certain recent types to which it exhibits a very close 
resemblance, particularly Selaginella rupestris Spring. In its densely 
tufted habit, small leaves, and slender branches this “ most widely- 
spread species of the genus”, 4 which does not occur in Europe, is 
strictly similar to the fossil form. The agreement presented by 
the vegetative shoot extends to the spores : the microspores, 0.45 
mm. in diameter, have a finely reticulate or pitted exine, and the 
megaspores, 0.4 mm. in diameter, are characterised by the same 
1 Lyon (’01) : the expressive term pebbled is used in describing the exine 
of the microspores of Selaginella apus, which agree closely with those of 
Selaginellites Dawsoni. 
2 For good figures of recent spores, see Hieronymus (’02). Some mega¬ 
spores of species of Selaginella are figured also by Bennie and Kidston (88), PI. 
vi, figs. 22-24. 
2 Fitting (’00), PI. vi, fig. 23 ; Heinsen (94), PI. xvi, figs. 5-7. 
« Baker (’87), p. 35. 
