characters except in size with his specimens. I trust, therefore, 
that in adopting the specific name I am not committing an error, 
although, were I to form my judgment of C. decurrens on the 
diagnosis assigned to it by its founder, I should not have referred 
to it the specimens here figured. 
Our C. decurrens seems to be almost exactly intermediate 
between C. rubrum and C. diaphanum. It agrees with the 
former in size, but differs in having a translucent space, destitute 
of coloured cells, in the middle of each internode. From C. dia- 
phanum it differs chiefly in having the lines of coloured cells 
which clothe the nodes continued over a considerable space of 
the articulation, and thus, as it were, decurrent along the stem. 
The exact disposition of these cells, and the structure of the 
stem, is well seen when a longitudinal slice is taken, as at fig. 4. 
The minute coloured cells will then be found immersed in the 
transparent walls of the frond. 
I have seen no other specimens than those found at Torquay, 
one of which is here figured. There is a variety of C. rubrum 
which I once confounded with C. decurrens, from its having a 
pale or transparent band in the centre of the internode ;—but 
this variety, when examined more closely, will be found to have 
the whole of its walls traversed by strings of cells, but having 
those of the centre part colourless or pale. 
Fig. 1. CERAMIUM DECURRENS, 8. majus:—the natural size. 2. Apex of a 
branch. 3. Articulations fecnn the middle of a branch. 4. Vertical section 
of the same :—all highly magnified. 
