purple shade on drying, after immersion in fresh water. Sudstance very 
tender and soft, cartilaginous in the stem and branches, gelatinous in the 
ramuli, closely adhering to paper. 
eae 
A very beautiful species, in many respects resembling P. 
jibrata, especially in the appearance that small portions present 
to the microscope ; but this is a much larger and finer growing 
plant, and readily and clearly distinguished by the opake stem, 
coated with short, irregular cells. In some specimens the byssoid 
ramuli are much developed, and of a beautiful violet colour, 
especially when dried ; m others they are far shorter, and the 
frond has a more bushy appearance. In a young state the tips 
are found clothed with fibres, but these are rarely seen in the 
more advanced stages of growth. 
From P. Brodiei, to which luxuriant specimens bear much 
resemblance, P. violacea is at once known by the fewer number 
of tubes in the stem; the siphons in that species being seven in 
number, whereas in this there are but four. 
The species called P. violacea in the British Flora, on the 
authority of Carmichael, is very different from the present ; but 
so near P. nigrescens in its essential characters that 1 am now 
disposed to regard it as merely a variety of that species. I had 
at one time kept it distinct under the name of purpurascens. 
Every one acquainted with P. xigrescens must know that it puts 
on a great variety of shapes, and the state formerly called vzolacea 
differs from the usual forms in beimg of a brighter and more 
purple colour, with greater delicacy of ramification. 
Our present P. violacea was first detected as British by Mrs. 
Griffiths, and ascertained to be identical with the plant of conti- 
nental authors by Professor J. Agardh, who inspected the speci- 
mens published in the early copies of Mrs. Wyatt’s books. It 
has been found on most of our coasts, and is probably distri- 
buted round the shores of the British Isles. 
7 
Fig. 1. PotystPHoNIA VIOLACEA:—the natural size, 2. Ramuli with ¢etra- 
spores. 8. Ramulus removed. 4. A tetraspore. 5. Fibrilliferous apex. 
6. Ramuli with capsules. 7. A capsule. 8. Portion of the stem, to show 
its surface cells. 9. Transverse section of the stem, to show the siphons. 
