226 BRITISH MARINE ALG. 
plant are rarely an inch high. The branches are very short, slender, and 
erect, and lie very close to the filaments from which they arise, which 
is usually near the tips. The joints are about twice as long as broad. 
Tetraspores are the only form of fruit I have met with on this species. 
They are produced in clusters of twos and threes, on the tips of terminal 
branched ramuli, as seen at a, Fig. 205. The colour isa deep purplish red. 
A variety of this plant, called C. purpwrewm, is known by its more minute 
filaments, which are very sparingly branched. The little velvet-like tufts 
are found sometimes on marine rocks in long purplish-red masses, scarcely 
a quarter of an inch high. C. floridulum (Fig. 205), which is so common 
on the west of Ireland that it is carted away from the shore and employed 
as manure, is found in various situations in this country and in the 
Orkneys. I have taken lovely specimens of it at Hastings and at Ply- 
mouth. The filaments are produced in dense erect tufts about an inch 
and a half high, slightly-branched, and furnished with a very few terminal 
branchlets or ramuli, which are densely appressed or arranged almost 
parallel with the branchlets from which they spring. The joints of the 
stems and branches are nearly all about three times as long as broad. 
The fruit of this species, which was discovered by Mr. Ralfs, the well- 
‘known naturalist, consists of very minute tetraspores, which are borne 
on tiny little pedicels, usually in a series of three, ranged on the outer 
side of the terminal branches. A fruited filament 1s represented at b, 
Fig. 205. The colour is a pretty mixture of crimson and purple, and 
when plants in good condition are carefully mounted on paper they 
make very attractive book specimens; as in drying, the filaments 
have the soft texture and glistening appearance of tufts of floss silk. 
C. mesocarpum (Fig. 205), so named from the situation of the tetrasporic 
fruit, which is produced on single or forked pedicels about the middle of 
the little erect filaments, is a very minute and a very rare species, found 
originally at Appin, in Scotland, by the late Captain Carmichael, and 
once only by myself in Lamlash Bay. Portion of a filament bearing 
tetraspores is represented at c, Fig. 205. The joints of the tiny fronds 
of this plant are about four times as long as broad. The colour is a 
brownish red or purple, and, to the unassisted eye, the whole plant 
appears like a mere. dark reddish crust attached to the rock on which 
it grows. The last section of this lovely group of seaweeds contains 
two or three species, which are minute parasites, and, like several of the 
foregoing, are hardly distinguishable as vegetable structures, unless they 
are examined under a tolerably powerful microscope. However, as each 
_ species is pretty constant to some particular plant, which the student will 
easily recognise, a very slight examination of the decaying fronds of those 
I am about to name, will doubtless reward the collector for his search 
after these microscopic Callithimnie. It has often been said that the 
roots of the great Laminariw, which are thrown ashore after a storm, 
are a mine of wealth to the zoologist ; and certainly, if properly examined, 
old fronds and stems of the same species are frequently rich in micro- 
