and failed to detect any character which may not be found more
or less strongly marked in some specimens of P. elongata, so
that these two forms are easily traced into one. Of the three
species quoted from Kiitzing, I have only seen one authentically
named ; the other two were communicated by M. Zanardmi, on
whose authority my specimens rest. Judging by the specimens
I have examined, as well as by the descriptions given by Kützing,
I have no hesitation in referring them to P . elongata; and
probably several other species described hy Kützing in the same
section might also be added without impropriety.
Dr Greville’s P. rosea has much more the aspect of a distinct
species than any of those already alluded to. It seems confined
to deep water, and is much more flaccid than ordinary P . elongata,
almost gelatinous, closely adhering to paper in every part,
and of a brilliant rosy crimson colour. It was first found by
Sir John Richardson among rejectamenta in the Prith of Porth,
and has been more recently dredged near Carrickfergus by the
late Mr. M'Calla, from whom I have excellent specimens.
I should mention another plant recently found in Cork Harbour
by Lady Louisa Tenison, which seems almost intermediate
between P. elongata and P. elongella, but different from both.
At present I hold it over for future determination. P. Grevilhi,
Harv., appears, from a recent analysis, to be nothing more than
P. violacea, of a brighter red colour than usual.
F d 1 . P o l y s i p h o n i a e l o n g a t a , a plant of the second y e a r : - ^ « m tural.
° she. 1. Eamulus with ceramidia. 3. Portion of one of the smallei
branches. 4. Transverse section of the same. 5. Eamuh with tetra-
—all 1
h V i