form of that very variable species, from the normal state of which
its clearly articulate stem affords a ready distinctive character.
The habit of branching strikingly reminds us of P. elongella, but
in no other character does it agree with that species. There is
also an affinity with P. violacea and P. fihrata, and especially
with P. Griffithsiana; hut from all these it differs in more or
less degree, and with none, except the last, has it a very strong
relation. With the view of attracting the attention of collectors
to the subject, and thereby clearing up the doubts which I cannot
help entertaining respecting the validity of the species, I have
given it an early figure. Nothing is known respecting the manner
or place of its growth, hut very probably it is a parasite on some
of the smaller Algse; and most likely an annual, and found in
the summer season.
Fig. 1. POLYSIPHONIA R ic h a k d s o n i :— natural size. 2. Apex of a branch:
—magnified. 3. Portion of the stem. 4. Portion of an upper branch.
5. Transverse section of the stem. 6. Capsule or ceramidium:— all more