long, cylindrical lower articulations ; and this much is generally
sufficient to ascertain the species. But I observe, on some
specimens, especially those from the South of England, an
occasional prolongation of the upper angles of the articulation,
showing a tendency to approach J. corniculata. Still, I have
never seen a thoroughly intermediate specimen.
Several exotic species nearly resemble J. ruhens in habit,
differing chiefly in size and in the comparative length of the
articulations.
Fig. 1. J a n i a b u b e n s , growing on .-— o f the natural size. 3. A
branch. 3. Ceramidium. 4. The same, after maceration in acid. 5. Tetraspores.
6. An articulation, from wliich a transverse slice has been
removed, showing the internal structure:— all i
