The Marine Algæ of Iceland. 



(II. Phæophyceæ.) 



By 



Helgi Jonsson. 



Phæophyceæ. 



Fam. Myrionemaceæ. 



Lithodenna fatiscens Aresch., emend. Kuckuck Bemerk. I, p. 238. 



This species is found on rocks, stones, shells and on other algæ. 

 It belongs to the sublitoral region and has been found down to a depth 

 of 12 fathoms, but 1 have also sometimes met with it in the lower litoral 

 region on stones or other algæ. Once I have found it in a pool above 

 high-water mark, growing on Ghætomorpha Melagoniuni, on a much ex- 

 posed coast, where only spray of the surf could reach it; the specimen 

 was well agreeing with the typical form, and had young unilocular spo- 

 rangia in July. 



My material of this species has been gathered in the spring- and 

 summer-months, and is for the most part sterile. I have only in June 

 and July met with some few plants having young unilocular sporangia. 



E. I c el. Vattarnes. 



N. Icel. Grjötnes (CO.): Eyjafjöröur. 



NW. Icel. Prestsbakki; Isafjöröur (CO.); Dyrafjöröur (Ldbk.). 

 SW. Icel. Melar, Stykkishölmur ; Keflavik by Snæfellsjokull (CO.). 



Petroderma maculiforme (Wollny) Kuck. Bemerk. II, p. 382. 



The specimens I have referred to this species agree well with 

 Kuckuck's description (I.e.). The thickness of the filaments was 7 — 9//, 

 and the unilocular sporangia were 14// long and 10// broad. As a rule 

 Botanisk Tidsskrift. 25. Bind. 10 



