ORGANIZATION OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 915 
between macrospores and microspores. In both we find a-thick exosporium, within 
which, and somewhat separated from it, is a much more delicate membrane, which we 
will term the endosporium. In the case of the macrospores, the exosporium is often 
somewhat flattened at the surfaces of contact of the rather closely packed spores. 
Within the endosporium, in both microspores and macrospores, is usually a relatively 
small, dark-coloured mass, probably representing the carbonized remains of the 
cell-contents. 
The more recently discovered specimen is, in one respect, better preserved than the 
one originally described. In the latter, the endosporium is almost always somewhat 
shrivelled, in the case of both micro- and macrospores. In the former, the endo- 
sporium has usually retained a perfectly spherical form; the exosporium, however, 
has often, to some extent, split away from the inner layer. 
It may be mentioned that in one or two cases the exosporium appeared to be 
double, so that, very probably, an episporial membrane was present, but cannot 
usually be distinguished. 
In the case of the small abortive spores, associated with the macrospores, it was not 
possible to distinguish the separate layers of the cell-wall. 
CALAMOSTACHYS, sp. ? 
A specimen of Calamostachys from the Oldham Coal-Measures, shows a somewhat 
different habit from C. Binneyana (see Plate 74, photographs 17 and 18). Both 
bracts and sporangiosphores have the same obliquely upward direction which we 
observed in C. Casheana. Five whorls of sporangiophores, with their sporangia, are 
present in the specimen. The latter are filled with small spores (not associated in 
tetrads), which agree precisely in dimensions with the microspores of C. Casheana. 
It is possible that the specimen may belong to that species, the macrosporangia not 
being preserved. No certain conclusion, however, can be drawn, except that the 
specimen is at any rate not identical with C. Binneyana. 
AFFINITIES OF Calamostachys. 
The description given of the structure of the strobilus in the homosporous and the 
heterosporous species, leaves no doubt that both must have been the fructifications of 
Calamariese. In view of the close agreement in structure which we have been able to 
demonstrate, the suggestion of M. Renavutr that while the heterosporous forms are 
obviously cryptogamic, the others may represent the male flowers of seed-bearing 
plants, appears to us to be quite untenable. . 
The whorled appendages, the constant presence of a medulla, and of primary 
medullary rays, and the collateral bundles with centrifugal xylem, form a combination 
of characters peculiar to the Calamariese among the known Cryptogams of the 
