114 BRITISH MARINE ALG&. 
upon other species they are colourless, in this they partake of the usual 
crimson or brown-red tint of the plant.’? The structure of this species 
under the microscope is remarkably beautiful, every portion of the stem 
and branches being distinctly jointed, and the dissepiments or separations 
between the articulations being perfectly pellucid or transparent. The 
siphons are seven, and surround a colourless tube. Fig. 107 represents two 
highly magnified branchlets. The capsules, seen at a, are very elegant 
in form, and are produced on short stalks from the upper sides of the 
articulations. The tetraspores at b, are arranged in a single series, being » 
transformations of the three central joints of the branchlet which bears 
them. This handsome species is widely distributed. I have taken it 
frequently at Hastings, but much more abundantly at Ventnor, and still 
more so, and in very great luxuriance, at Plymouth. The fronds are from 
6in. to 14in. long, the colour is a fine deep red, which generally changes 
toa brownish red in drying. P. variegata is a remarkably beautiful 
species, and, although widely dispersed, is rare on the British coasts. I 
have taken it abundantly in the muddy rocky nooks about Plymouth, 
but nowhere else. It grows in dense tufts from 5in. to 12in. long. The 
filaments are very slender, and are attenuated upwards to the most delicate 
hair-like fineness. The upper portions of the plant are a beautiful pur- 
plish-red, which is usually retained in drying. A transverse section of the 
stem is seen at e, Fig. 101. The siphons are six, surrounding a colour- 
less central tube. When viewed under the microscope, the joints of the 
base are broader than long, and in the main branches twice as long as 
broad; those in the ramuli are short, but they are distinctly marked 
with three dark coloured oblong tubes. These characters, which are* 
pretty constant in this species, serve to eo it from others 
which it somewhat outwardly resembles. 
I much regret that the extreme difficulty of preparing satisfactory illus- 
trations of this beautiful tribe of plants in the growing state, permits . 
merely a brief mention of many species I would otherwise gladly describe. 
The noble species P. Brodiwi, which I have taken in the Clyde and on 
the Mewstone Rock, near Plymouth, the branches of which were upwards 
of 20in. long, would require a plate of folio size to give a fair idea of its 
grandeur. This species may be known by its large spreading branches, 
which are alternate and have each a distinct main stem throughout. The 
stems usually contain seven siphons, the ramuli three or four, rather 
longer than broad. The colour is a dark brownish-red. P. violacea is 
a beautiful reddish-purple plant, the fronds of which are from 6in. to 12in. 
high, having a principal main stem set throughout with long alternate 
branches gradually diminishing in length upwards, all of which are 
branched again and again, and terminate in tufts of exceedingly slender 
ramuli. These ultimate ramuli give a pretty feathery appearance to the 
plant, and in mounting on paper, clot together, and so display the beautiful 
purple tint of the species to perfection. The joints in the stem, which are 
very indistinct, are usually marked with irregularly shaped tubes. In the 
