430 



disc and the erect filaments 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 specimeiis I have examined 



were sterile. 



Found hitherto in the following piaces: — Vid. (H. J.); Bordo: 

 Haraldsund (!); Kuno (H.J.); Ost: Glibre (H.J.); Str.: Kalbakfjord (H.J.), 

 between Thorsvig and Kvalvig (!), Gliversnæs (!). 



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 crusl ; such crusls are sometimes 

 of considerable extent, thus, in a large, Hal rock-pool, near Vaags 

 Ejde on the wesl coast of Sydero, which contained only :i few 

 inches of water at ebb-tide, Ralfsia verrucosa occurred over an 



