RHODOSPERME.®. 215 
bearing on the inner face of the terminal angle a large favella. 
Tetraspores, when present, are similarly situated to those of the foregoing 
species. I have always found this pretty plant growing on the tips of 
Laminaria digitata (Fig. 46). Many years ago I took a large number of 
> specimens in fruit, all of which were growing on the Laminarie outside the 
well-known Mewstone Rock near Plymouth; and some years later I found 
portions of the fronds of L. digitata cast ashore one stormy day at 
Atherton, in the Isle of Wight, every one of which had a fringe of this 
lovely Callithamnion, both kinds of fruit being found in abundance 
among the numerous specimens I collected on that occasion. The fronds 
of this species in the barren state are occasionally above 5in. long, but no 
specimen taken by me, in either kind of fruit, ever excedeed 2in. in length. 
The colour is generally a rich deep red. C. Brodiwi (Fig. 197), although 
widely distributed in Britain, is certainly by no means abundant in any 
recorded habitat. I have taken it in fine condition at Plymouth, and 
occasionally in Torbay. The fronds are rarely over two inches high, 
densely branched, and set throughout with several series of branchlets, 
which gradually shorten upwards, and all are furnished with tiny winged 
plumules, the little spine-like pinnz which compose them standing. 
out almost at right angles from the joints from which they arise, 
being what is termed “ erecto-patent.’”’? In plants which bear favelle, 
the branching is much more irregular than in those which produce 
tetraspores. The favelle are attached in pairs, one on each side of 
the stems of the branchlets, as seen at 6, Fig. 198. The tetraspores 
are globular in form, and are seated on the inner face of the terminal 
ramuli, which‘ are thrown out in pretty regularly alternate order on 
each side of the lesser branches. I have usually found this rare plant 
on the Fuci at extreme low water mark. The colour is a deep brown- 
red, but loses much of its brilliancy in drying. C. Hookeri (Fig. 197), named 
after the late Sir W. J. Hooker, is also widely distributed in this country, 
but must be considered among the rarities, as it certainly is one of 
the favourites of its tribe. It grows on several species of algx, but I 
have only found it on submerged rocks, near low-water mark, at 
Bovisand, near Plymouth. The fronds of this lovely little plant are 
seldom more than two inches high, and are closely set with rather long 
branches, which, near the tips, bear a second and even a third set; 
and on the terminal or central plumules of the lateral branches the 
pretty pair of oval or lobed favelle are produced, loosely attached to 
each side of the joints, as seen at c, Fig. 197. Tetraspores are seated 
on the inner face of the ramuli on the joints nearest to the stem; 
sometimes they are placed on each side of the ramuli, one or two under, 
and several above. The colour is usually a brownish-red, or sometimes a 
rosy-red; young plants generally retaining their beautiful tints in drying. 
C. tetricum (Fig. 198 and 199) is one of the coarsest and most common 
species of this genus. It is perennial, and is found on all the rocky 
coasts of Britain, hanging from the under side of ledges of rock, whence 
