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Selaginella spinulosa. This is a feature, however, which I have 
never noticed in the coal spores, and had it been common to 
them I should certainly have seen it. I think, however, that 
coal spores more closely resemble in appearance the Selaginellee 
or Isdéetec than to any other class of modern vegetation, but there 
are now classed by Sacu apart from the Lycopodiacee, under 
the head of the LIngulate. Quite recently Professor P. F. 
Retyscu has figured a number of Carboniferous spores, some of 
which are closely allied, if not identical, to some of mine, 
and he gives to them the name Triletee. In speaking of 
them he says,* ‘‘ The Triletee are spores of Cryptoganic plants 
more highly developed, and if this supposition be correct the 
Triletee can only be derived from Lycopodia and plants much 
resembling them. Future investigation will no doubt throw 
more light on the problem, but one thing seems clear from 
my investigations, as far as they have gone, namely, that coal 
originated from one class of vegetation; and I venture to predict 
it will be found to be of aquatic habit, and that seams of coal 
originated in a manner not unlike that of modern bog growth. 
In concluding this paper I desire to return my thanks 
to Professor Harker, of the Royal College of Agriculture 
Cirencester, for his kindness in helping me examine my slides. 
He considers that some of the coal spores may be allied to the 
modern genus Isdetew, and suggests the generic title of Isdetoides 
pending further investigation. 
* Micro-Palaeo-Phytologia. Formation Carbonifera. Introduction, p. iv. 
