metamorphosis of one of the prongs of the terminal forks. e¢raspore 
immersed in the terminal ramuli. Antheridia abundant m winter and 
spring, bright yellow, crowded close to the ends of the branches, oblong, 
affecting the colour of the tuft by their abundance. Substance rigid, not 
adhering to paper, except after long steeping. Colour a rich vandyke 
brown, becoming foxy im age or decay. 
RR nnn nn mnnnnnnn 
A very common species on the shores both of Europe and of 
North America, almost invariably infesting Mucus nodosus with its 
dark brown bushy tufts. Occasionally I have seen it growing 
on F. serratus and LF’. vesiculosus, but it is much less common 
on them. On the contrary, wherever /. nodosus occurs, there 
it is accompanied by this parasite. Pol. fastigiata grows nearer 
to high-water mark than any others of the genus, and is generally 
exposed, for many hours of each tide, to the influence of the air. 
This exposure and the constant alternation of circumstances pro- 
bably influence the colour of its frond, and we accordingly find 
that it partakes of the drown tints of the uct among which it 
grows, almost to the entire extinction of the red colour, proper 
to the family to which its structure allies it. Besides this dif- 
ference of colour, it differs from most others of its genus in 
having a cell, containing endochrome, within each articulation 
of the central or axial tube. In this respect it partakes of the 
character of Bostrychia, with which genus its colour and habitat 
strongly connect it. The autheridia are particularly abundant 
and of large size; and at the season when they are developed 
the tufts become of a yellow or orange colour. Almost every 
point of the branches bears its tuft. 
It is difficult to account for the specific name, polymorpha, 
under which it was designated by Linnzeus, for few species 
among the marine Algz are less inconstant in character. 
Fig..1. Tufts of PoLystPHONIA FASTIGIATA growing on Fucus nodosus :—the 
natural size. 2. Portion of a frond, to show branching. 3. Ceramidia. 
4. Branchlet with imbedded tetraspores. 5, A tetraspore. 6. Apices 
with antheridia. 17. An antheridium. 8. Portion of a frond, partly cut 
longitudinally to show the internal structure. 9, A transverse section of a 
frond :—all magnified. 
