106 
part of each undivided disk gave off a large number of 
slender sporangiophores, many of which ran along the upper 
surfaces of the disks and bracts to reach the more peripheral 
sporangia. These sporangia were large and conspicuous — 
those belonging to each segment being arranged nearly in a 
plane parallel to the disk — and in four irregular concentric 
circles. Each sporangium appears to have been attached to 
the disk by a separate sporangiophore. The spores were 
very numerous and perfectly orbicular, but their minute 
organisation, like that of the cells and vessels of the oi’gan- 
ism, was masked by the mineralisation which it had under- 
gone, being preserved in a highly crystalline carbonate of 
lime. The author then proceeded to examine the probable 
affinities of the several forms of strobilus of which the 
structure is now known. One, which he previously described 
in the Memoirs of the Society he assigns to Calamites. 
The other two, viz., that originally figured by Mr. Binney 
and that now described, he believes to belong to the Annu- 
larian forms of vegetation. Two varieties of verticillate 
foliage have most probably been confounded under the 
names of Asterophyllites and Annularia — the one being that 
of the Calamitean plants, the other belonging to the genera of 
Asterophyllites and Sphenophyllum, and it is to one or the 
other of these two genera that the strobilus now described, 
as well as that figured by Mr. Binney, appear to belong. 
The structure of their central axes is what the author chiefly 
relies upon in arriving at these conclusions. The name of 
Volhnannia Dcnvsoni is provisionally proposed for this new 
strobilus, in honour of the distinguished Principal of M’Gill 
College at Montreal, and in recognition of his valuable eluci- 
dations of Canadian phytology. 
