62 
from f. linearis through f. vulgaris to f. laciniata (comp. Taurer in LE Joris Liste 
p.100). In f. vulgaris the longitudinal axis of the frond is much longer than the 
radii going outwards or downwards, but under the continued growth of the frond 
in transverse direction this difference diminishes and at last entirely disappears, 
the frond obtaining an approximately orbicular outline, at the same time becoming 
more or less laciniated and, on account of the continuous transverse growth, much 
radially folded (Plate I fig. 2). The point of attachment in this stage is only appa- 
rently, not really central and umbilicate, as supposed in the older descriptions and 
drawings (LINNÉ, Spec. plant. II 1763, and Dırrenıus, Hist. muscor. 1741, tab. 8). 
Though the f. linearis normally disappears in spring on the Danish shores, it 
can however be found much later in the year if rarely. Thus I have met with it 
on the outer side of the northern mole of Frederikshavn, near the entrance of the 
harbour, at a place where the sea is as a rule agitated, in July 1895 and September 
1892. The specimens found in September were very well developed, up to 30 cm. 
long, 0,5 to 1,3 cm. broad, fully typical, only of a lighter colour than the specimens 
occurring in winter. These discoveries, however, may be very rare exceptions, for 
I have otherwise never found this form in summer at Frederikshavn, one of the 
best investigated localities in Denmark, as little as in any other locality. ARESCHOUG 
has also found it in August on the shore of Bohuslän (Phyc. scand. mar. p. 180). 
This species has been met with in all the months of the year, and it occurs 
at all seasons in fully developed specimens. It can probably attain an age of more 
than one year, but most of the specimens die, as said above, at a rather young 
age. It has been found fertile at all seasons, and then nearly always with sexual 
organs (or carpospores). While several authors state that the species is as a rule 
dioecious (THURET, BERTHOLD, Kyrın), I have found it most frequently monoecious 
on the Danish shores, at all events in summer. In winter only have I found the 
specimens generally dioecious, particularly f. linearis (Plate II fig. 2—3). In the spe- 
cimens met with in summer the frond is generally divided by a longitudinal limiting 
line into a male and a female portion, distinguishable thereby that the margin of the 
first is yellowish white, that of the second purple. The limiting line is most often re- 
markably straight; it is very distinct towards the margin, while downwards it be- 
comes indistinct and finally vanishes on reaching the sterile portion of the frond 
(Plate I fig.1). The male and female parts of the frond are in some cases of equal 
size, in others the male or the female is broadest. Even the narrow winter forms 
can be monoecious and show a well marked limiting line (Plate II fig. 1). According 
to Hus (1902, p.197), the sporocarpia and antheridia in Porphyra laciniala (umbili- 
calis), when they are developed in the same frond, “occur in patches very much 
as in P. perforata”. If that is really normal to the species of the Pacific coast, it 
must be supposed that it is a different species from the European P. umbilicalis. 
The decoloration of the developing antheridia generally takes place gradually 
from the margin inwards. Some few specimens from Helsingør showed however, 
at some distance from the margin, some lighter spots, reminding one of the an- 
