158 BRITISH MARINE ALGA. 
of the most elegant of the branching series of British alge. It is also one 
of the easiest to display on paper; its fine shrub-like branches being 
tolerably fiat, and presenting few difficulties in arranging, even to the 
most inexperienced manipulator. The fronds arise from a fibrous root, 
and are from 3in. to 12in. high. They are very much branched and bushy, 
but vary greatly in the size and breadth of stem and ramuli, according to 
the depth of water in which they grow. Their beautiful little compound 
or comb-like ramuli, on specimens found in shallow rock pools, are so fine 
and closely set, that, without recourse to a magnifier, I have often known 
collectors mistake such plants for Callithamnia; but specimens which are 
cast up from deep water have broad fiat stems, even in the second and 
third series of branches ; the numerous sets of awl-shaped ramuli which are 
set in rows like the teeth of a comb, chiefly on the inner face of the 
branchlets, are distinctly-apparent even to the naked eye, and, when once 
known, serve to distinguish this favourite species at a glance. The colour 
of this plant is generally a bright red, and specimens may he mounted 
equally well in sea or fresh water ; in fact, I have picked up plants on 
the shore after a heavy shower of rain, that were of the deepest crimson; 
but on exposure to strong sunlight for any length of time, the fronds 
become perfectly white or colourless. The capsules of Plocamiwm are 
about the size of small poppy-seed, and are seated on the sides of the 
upper branchlets. Tetraspores are contained in little star-like receptacles 
called ‘‘ stichidip,” which:are seated on the inner face of the ramuli; but 
as they are strictly microscopic a strong lens is necessary even to detect 
them. One of these branvhed receptacles is represented at Fig. 146. The 
tetraspores are scattered near the tips of the terminal divisions. 
‘The genus Cordylecladia is represented on the British shores by the 
solitary species ‘Cordylecladia erecta, a complete plant of which is repre- 
sented the natural size at Fig. 147. This rare little alga was formerly 
included in the. genus Gracilaria. Its new name signifies “chord,” or 
“ string-like branch.’? The fronds, which are tufted and very sparingly 
branched, grow up from a disc-like base, which is usually so imbedded 
in sand that the: -apper portions only of the little erect stems are visible ; 
and this peculiarity of habitat, in connexion with the small size of the 
plant, may probably account for its rarity; for although it is widely 
distributed along the shores of the British Islands, specimens are by no 
means abundant, either in public or private collections. The fronds are 
rarely over 2ing high ; the’ plant grows in rock pools, is perennial, and 
fruits in winter. The capsules of this species are very prominent, and 
are produced, ore or less abundantly, in clusters, or on each side of 
the upper parts of the stems and branches, as seen in our illustration. 
The colour is a’ dull red, ‘the substance is stiff and rigid, and the plant 
does not readily adhere to paper; therefore when specimens are dried, 
I recommend an application, to the under side of the stems, of the 
mixture made from isinglass dissolved in spirits of wine. 
The Cryptonemitcere “are an extensive Order of plants, which may be 
