HICK : CALAMOSTACHYS BIXXEYANA. 
289 
Aii examination of fig. 5, a, PL II., will show that the thin -walled 
t issue of the peduncle is continued into the sporangium where it 
forms a non-sporogenous tissue, filling up the somewhat conical base 
In other sections a thin layer of this tissue may be traced all round 
the interior of the sporangia, where it bears some resemblance to the 
compressed cells which, as a tapetum, surround the archesporiuin of 
some of the Vascular Cryptogams. Moreover this layer is often 
found separated from the outer wall of the sporangium, and then the 
spores seem to be contained in a delicate bag, quite distinct from the 
wall itself. That this condition is one which preceded the full 
maturation of the spores seems probable from the fact that in the 
specimens where it occurs the spores are still grouped more or less in 
tetrads, and enclosed in the mother cells, and I incline to the opinion 
that the separation was brought about during the process of 
fossilisation. 
The Spores. 
As in the case of the sporangia the spores have been carefully 
described by previous writers, and I have no additional details to 
bring forward. As to their character, it may be noted that in none 
of the sections studied has any indication been found that this 
species of spike was heterosporous. Slight differences of size and 
appearance are sometimes met with, even between spores in the same 
sporangium, but these are not greater than those that occasionally 
arise in the homosporous sporangia of recent plants. So far then as 
is known up to the present time this species of C<daiiio*t<jj:hys is 
homosporous. 
S vst em a tic Position. 
If the preceding description has not failed in its object it will 
have convinced the reader that in Calamostachys Binneyana we have 
a sporiferous spike whose structure has many points of resemblance 
with that of Equisetum. The resemblance is so close and involves so 
many details that it is impossible to do otherwise than conclude that 
it is the strobilus of some carboniferous plant whose affinities are 
more or less close with the existing genus Eqidsetum, Such a plant 
we have in Catamites, and hence Carruthers* did not hesitate to 
* Loc. cit. 
