Sporangia plane, umbilicate, attached to the wall by an elastic cord.
Umbilicate: Having a central pit or depression (Fig. 143, f).
Umbilicate, depressed in the centre, like the ends of an apple; with a navel.
The latter is usually very short, almost completely concealed in the concavity of the umbilicate sporangium.
Sometimes they are umbilicate below, so that a vertical ...