430 
disc and the erect fdaments formed a parenchymatous tissue an¬ 
swering to Wille’s description. Further, only one chromatophore 
occurred in the cells. Fully developed sporangia I have not met 
with, but notwithstanding this drawback, I have no doubt as to 
the correctness of my determination. 
Found only on Str.: Thorshavn (!). 
LITHODERMA Aresch. 
109. L. fatiscens Aresch. 
Found in the sublittoral zone at a depth of 2—20 fathoms 
both in the open sea and in the interior of fjords. It grows some¬ 
times on stones and sometimes on shells. It was gathered in June, 
July, October and November, but the specimens I have examined 
were sterile. 
Found hitherto in the following places: — Vid. (H. J.); Bor do: 
Haraldsund (!); Kuno (H.J.); Ost.: Glibre (H.J.); Str.: Kalbakfjord (H.J.), 
between Thorsvig and Kvalvig (!), Gliversnses (!). 
PETRODERMA Kuck. 
110. P. maculiforme Kuck., Bemerkungen, II, p.382. 
Some small, brown patches occurred on smooth rock-faces close to 
high-water mark near Saxen (Str.), which on a closer investigation 
were seen to be caused by the growth of a small alga seemingly 
precisely similar to the present species. A chromatophore occurred in 
the cells, which corresponds to Kuckuck’s description, and both the 
unilocular and plurilocular sporangia exactly resembled Kuckuck’s 
figure, with the exception that the unilocular sporangia were some¬ 
what larger than he described them. 
Found only on Str.: Saxen (!). 
RALFSIA Berk. 
111. R. verrucosa (Aresch.) J. Ag. Reinke, Atlas, pi. 5 and 6, 
figs. 1—13; Kjellm., N. I., p. 309 (249). 
This species belongs to the littoral zone and grows by prefe¬ 
rence on exposed coasts, where it occurs associated with Hilden- 
brandia especially in rock-pools, covering the bottom of the latter 
with a rough, yellowish-brown crust; such crusts are sometimes 
of considerable extent, thus, in a large, flat rock-pool, near Vaags 
Ejde on the west coast of Sydero, which contained only a few 
inches of water at ebb-tide, Ralfsia verrucosa occurred over an 
