198 BRITISH MARINE ALGA. 
‘ramuli. C. acanthonotum, the last of this group, grows’ generally on 
exposed rocks, or on the fronds of other plants, near low-water mark, 
in dense dark purple tufts, from 3in. to 6in. high. The favella of this 
species is as round as a ball (as represented at c, Fig. 184), and is seated 
on a curved jointed ramulus, every articulation of which (like those 
of the stems and branches of the plant), is armed on the outer upper side, 
with a single three-jointed prickle. In this respect it somewhat resembles 
C. flabelligerum (Fig. 182), but the coloured cellules in this are con- 
fined to the nodes, and the inter-spaces are perfectly hyaline, or colourless. 
When properly displayed, this species, like each of the two foregoing plants, 
makes a very attractive book specimen; but most of these ciliated 
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Fia. 184, (a) Joint of Ceramium ciliatum ; 
(b) Ceramiwm echionotum; (c) Three 
Fie. 183. Ceramium ciliatum. joints with ramulus and favella of 
Ceramium acanthonotum, 
Ceramiex are so entangled, by reason of their multitudinous spines, that 
the utmost patience and care are necessary to prevent the plants becoming 
an inextricable and unsightly mass. 
The genus Ptilota contains two remarkably beautiful plants, one species 
being common on the northern and western shores of Great Britain, the 
other being found in almost equal abundance in the south of England, and 
on some parts of the north-eastern shores, in Scotland, and in the Isle of 
‘Man. Fig. 186 represents an enlarged branch of Ptilota plumosa, or the 
* plumed wing.’’ The plant from which this was taken, was gathered by 
me in the Isle of Arran. It was growing on a huge specimen of 
Laminaria digitata (Fig. 46), encircling the stem of the great alga as witha 
feather-like collar of the richest brown-red colour. The fronds are 
from 4in. to 14in. long, and are beautifully and very copiously branched, 
