If this plant be really entitled to specific rank, it is well named
affine, for it appears to be akin to several other species, and to
form an intermediate link between them. To C. Hooheri it is
allied in habit, and in the opacity of the main stem, but here the
resemblance ends, for the nature of the ramification is extremely
different. With C. roseum we may also compare it, but the
narrow plumules, with short, erect pinnules, afford a clear mark
of distinction. Perhaps, after all, the nearest approach is to
C. polyspermum, which has plumules equally narrow, and pinnules
equally short, and which grows in similar places; but the solitary,
basal tetraspores of C. affine seem to point to another species.
In making the foregoing contrasts, however, it must be borne in
mind that I have compared C. affine only with the normal states
of the species referred to, and no one who has studied the genus
Callithamnion for any length of time, and in any considerable
number of localities, needs to be told that there are many intermediate
forms to which it is often difficult to assign the correct
name. In the present instance the difficulty has been cut, rather
than surmounted, by giving a name to one of these puzzling
forms; hut though this happened in 1832, no fortunate collector
has since met with specimens which could fairly come under
our C. I
Fig. 1. Callithamnion AFFINE ;— the natural size. 2. Part of a lesser branch,
with its alternate plumules. 3. Branch b e a r i n g 4. Branch with
on the ramuli. 5. A tetraspore on a ramulus. 6. SmaU portion
of the main stem ;— all more or It
I " J