218 KJELLMAN, THE ALG OF THE ARCTIC SBA. 
The stipe, 1. e. that part of the cauloid portion which does not produce sporo- 
phylls, is always short, usually 1—4 cm., seldom even 6 cm. long, terete, or upwards 
very slightly compressed, in old individuals even 8 mm. in diameter (tab. 25. f. 12). 
The rhachis, or that part of the cauloid portion which produces sporophylls, be- 
comes longer as the plant grows older. In certain specimens I have examined, it has 
a length of even 15 cm. It is compressed in its whole length, most so in the part 
that bears sporophylls at the time; there a transverse cut shows the narrowest ellipse 
with the longest longitudinal axis. Above the sporophylls it tapers swiftly, passing 
abruptly into the costa. Cp. tab. 25 fig. 18—15. Even in older specimens the rhachis 
is easily distinguished from the stipe, because through all its length it bears cicatrices 
of fallen sporophylls, the cicatrices being downwards thin, upwards very dense and 
forming small elevations on a ridge running on each side of the rhachis. 
The /amina is linear-lanceolate. In regard of the form of its base the lamina re- 
sembles that of A. esculenta f. muswfolia. I have not seen specimens with longer lamina 
than about one metre. In older individuals the lamina is usually 4—8 cm. broad at its 
broadest part; however, I have seen individuals in which the breadth of the lamina attained 
11—12 cm. In younger specimens the lamina is richly plicate and wavy, in older it is 
more plane and at the same time of firmer consistency. The lamina is thinner than 
in A. esculenta f. typica, resembling that of A. membranacea (tab. 20 and 21). 
The costa is broad, and very prominent, sometimes rising equally on both sides, 
sometimes more on the one side, passing immediately into the lamina (tab. 25, fig. 10). 
The sporophylls are elongatedly linear-linguiform, in younger specimens shorter, 
in older even 20 cm. long, usually 1,5 cm. broad below the top, sometimes even 2,5 cm. 
They taper strongly, but evenly, towards the base, passing almost imperceptibly into a 
pedicel 2—4 mm. long. While sterile they are membranaceous in the greater part of 
their length, and even after the zoosporangia have been developed, they are far more 
slender and less firm than in A. esculenta. They are always richly wavy and almost 
always twisted spirally several times downwards. Those first developed are thinly 
placed and distinctly separate, the following are densely crowded. In older individuals 
they are very numerous, densely clustered, sometimes 60 or wore in one individual. 
The sorus reaches from the base of the sporophylls to about two thirds of their length 
and is surrounded at the sides by a narrow, finely wavy margin. The zoosporangiferous 
part of a sporophyll is membranaceous-coriaceous, the rest of it is membranaceous 
(tab. 21). 
The zoosporangia are cylindrically spindle-shaped with blunt ends, about 40 w, 
long and 10—12 w. in diameter. As to these measurements it ought however to be 
remarked that I have had only a little number of specimens with fully developed zoo- 
sporangia at my disposal. 
The paraphyses are elongatedly wedge-shaped in optical longitudinal section, about 
10 uw. in diameter at the top. The outside of the membrane is thick and strongly 
eelatinized. 
Structure of the frond. In anatomical structure the present species offers several 
differences from A. esculenta. A cross cut of the stipe and the lower part of the rhachis 
