Didymium or Diderma, and as it has been regarded by almost
every author as belonging to the latter, I have thought it best
to allow it to remain in the same situation, and have formed
the generic character accordingly. I f this arrangement be approved
of, Didymium will include those minute plants which
are destitute of a columella, but have a double peridium.
D i t m a r has given an excellent figure of D . globosum in
S t u r m ’s Deutschland Flora.
J ■
Fig. 1 . D. globosum, m l. size. Fig. 2. A sporangium removed. Figs. 3. The
same, showing the pn-ogress o f dehiscence. Fig. 4. The remains o f a sporangium,
exhibiting the columella, Spc. Fig. 5. Sporules— All except Fig. 1.
more or less magnified.
U l
