outline, the branching being partly alternate, and partly dichotomous. 
The ultimate divisions, or ramuli, are more regularly forked, and level-topped, 
giving the tuft the appearance of being composed of innumerable minute 
corymbs, clothing the branches. Articulations of great length in all the main 
branches, destitute of veins, except towards the base of the stem and in 
very old fronds; those of the ultimate ramuli from three to four times as 
long as broad; all having a wide pellucid border surrounding the endo- 
chrome. Favelle generally in pairs, terminating the secondary branches, and 
sometimes surrounded by a few forked ramuli. Tetraspores solitary, sessile, 
placed just below the forkings of the ultimate ramuli. Colour a fine rosy 
red, sometimes brownish, soon changing to orange in fresh water. Sud- 
stance exceedingly tender, flaccid, and gelatinous,. adhering most closely to 
paper in drying. 
III wre 
A very variable plant: so much so, that most authors regard 
as distinct species two forms which I here bring together. 
Hitherto in British works we have recognized the original Cal. 
corymbosum of Eng. Bot., and the Cal. versicolor of Agardh, the 
differences between which are said to be, that the former is much 
more slender than the latter, with longer joints, a less evident 
stem, and a less pinnated branching. Some specimens are, 
indeed, very slender, and dichotomously divided, and others are 
robust, with an undivided stem and lateral branches ; but between 
the most extreme forms I have seen too many intermediate states 
to admit of my regarding them as belonging to more than one 
specific type. I have examined several authentic specimens of 
Agardh’s C. versicolor and compared them with our British 
plant so called, and can detect no differences between them. I 
therefore no longer hesitate to unite that synonyme to Cal. 
corymbosum. 
‘The nearest affinity of the present plant is with C. spongiosum, 
a species much more densely branched and bushy, of a browner 
colour, with a very robust stem and very short articulations ; 
but, like the present, remarkable for dichotomous, level-topped 
ramuli, and tetraspores placed opposite the alternate forkings. 
Fig. 1. CALLITHAMNION CORYMBOSUM, on a piece of Zostera leaf :—the natural 
size. 2. One of the ultimate forked branchlets, and some articulations of 
a secondary branch. 3. Ramuli with tetraspores. 4. A branch with 
favellee. 5. The favella removed. 6. Ramulus with (so called) antheridia. 
7. Veiny articulations from the base of the stem :—all magnified. 
