If this plant be really éntitled 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. Hookeri 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. rosewm 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. afine seem to point to another species. 
In making the foregoing contrasts, however, it must be borne in 
mind that I have compared C. afine only with the zormal 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 inter- 
mediate 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; but though this happened in 1832, no fortunate collec- 
tor has since met with specimens which could fairly come under 
our C. affine. 
Fig. 1. CALLITHAMNION AFFINE :—the natural size. 2. Part of a lesser branch, 
with its alternate plumules. 3. Branch bearing favelle. 4. Branch with 
tetraspores on the ramuli. 5. A tetraspore on a ramulus. 6. Small portion 
of the main stem :—all more or less highly magnified. 
