4 ROYAL SOCIETY OF CANADA 
These results are of interest as showing the relatively small extent 
to which silica enters into the process of fossilization in this case, and 
the large amount of organic residue retained by the body of the calcified 
mass. 
The several fragments of stems vary in diameter from 2 to 4 
cm.—differences which may be ascribed in part to varying age, and in 
part, also, to the removal of more readily separable external parts in 
some cases and their retention in others. The length was found to vary 
from one or two centimetres to upwards of 9°5 em. Upon careful exam- 
ination, this variation was found to result from the development of fre- 
quent transverse cleavage planes, proceeding from crystallization of the 
carbonate of lime, and several of these fragments were clearly parts of 
one stem in their original condition. The evidence in this direction 
seemed to point to the conclusion that even the largest specimen was 
only a fragment or small part of the original stem, a conclusion more 
fully sustained by subsequent study of the internal structure, and com- 
parison with stems of existing species of the same type. 
Although presenting certain individual differences of minor impor- 
tance, all of the specimens agree in their principal characteristics with 
respect to :— 
(1) General form and structure. 
(2) The development of numerous transverse cleavage planes. 
(3) The prevailing colour. 
(4) The appearance of strongly defined surface grooves and ridges 
parallel to the principal axis. 
(5) The very unequal distribution of these ridges on opposite sides. 
(6) The presence of emergent organs. 
A detailed consideration of these features will serve to more clearly 
define the character of the plant. 
The dominant colour is grayish black. Closer inspection, never- 
theless, shows that the surface ridges are frequently of a dull red colour, 
while the intermediate areas are a dull black. The polished transverse 
section is coal black, while the cut and unpolished surface is of a slaty 
black colour. 
Local crystallization of the calcite has resulted in the formation of 
numerous transverse cleavage planes, varying very greatly in thickness 
and in extent of separation. The more prominent of these occur at 
intervals of 10-12 mm., and they are often only 0-5 mm. in thickness. 
Through them the original stem has been broken up into shorter frag- 
ments, in consequence of which it is in some cases impossible to deter- 
mine the proper external aspect and dimensions from a single specimen. 
The less prominent of the cleavage planes occur at variable and fre- 
quent intervals, and they cause a breaking off of external parts in sucha 
