axis or string of large cells, which runs through the pinnule as well as 
(with some modification) through every part of the frond. Fructification ; 
1, roundish, tripartite, external tetraspores seated on minute pedicels, which 
fringe the margin of slightly abbreviated pinnules; 2, on distinct plants, 
clustered favelle, surrounded by an involucre of several subulate ramuli, 
and borne on the apex of abbreviated pinnules. Colour a dark, full red, 
occasionally with a brownish tinge. Suéstance cartilaginous, rather rigid, 
more or less perfectly adhering to paper in drying. 
Our figure and description apply solely to the var. a. of Turner, 
which, though abundant on the shores of Scotland and the north 
and west of Ireland, is rare in England, and quite unknown on 
our southern shores. As far as my experience goes it invariably 
grows on the stems of Laminaria digitata, which it often clothes 
with a rich feathery frmge. The var. 8. of Turner, which is the 
common plant of the south of England, as invariably grows 
on rocks ; and preserves its characters so constantly that I cannot 
help regarding it, with Kiitzing, as a distimct species. In doing 
so I am reluctantly compelled to dissent from the opinion of 
Mr. Turner, who says, “that no /wcus whatever exhibits more 
regular gradations between the most narrow and delicate, and the 
broadest and most cartilagmous individuals; in consequence of 
which no attempt was ever previously made to separate it mto 
different varieties.” I cannot observe this gradation ; to me the 
two forms appear to be easily distinguishable by the naked eye 
in every case; and present very distinct microscopic characters. 
Besides this, their geographical range and habitat are different ; 
for though on our northern shores both are found, yet further 
north the var. a. alone is met with; and further south, as on the 
southern shores of England and the shores of France and Spain, 
the var. 8. is exclusively seen. Add to this, that the first is never 
found on rocks, and the last always is; that the parasites which 
commonly infest them are different ; that one is a far stouter and 
more cartilaginous plant than the other; that the microscopic 
appearance of their pmnules is very dissimilar; and we shall, I 
think, have sufficient specific characters to separate them. 
Fig. 1. Prrtora pLumosa :—of the natural size. 2. A pectinated pinnule. 3. 
One of the ultimate lacinie. 4. An involucre. 5. Favelle, removed from 
the same. 6. A lacinia bearing tetraspores. 7. One of the tetraspores :— 
more or less highly magnified. 
