- 354 — 



Prasiola furfuracea (Mert.) Menegh., Imhäuser Prasiola p. 266; Fosl. 

 Gontrib. I, p. 127; Börgesen Fær. Alg. p. 486. 



The Icelandic specimens occur on rocks at high-water mark often in 

 company with P. stipitata, they agree fully with the description given by 

 Imhäuser (1. c.) and also with the Færoese specimens (Börgesen 1. c). 



E. I cel. Vattarnes; Hölmar. 

 N. I c el. Grimsey (O. D.). 

 SW. Icel. Reykjavik. 



Prasiola stipitata Suhr, Imhäuser Prasiola p. 272; Kjellm. Arct. Alg. 

 p. 303. 



The species occurs on rocks and stones at high-water mark. It is 

 much more common and gregarious than the last named species and it 

 often covers the rocks with a green growth. Probably common. 



E. Icel. Vattarnes, Brimnes, Borgarnes. 

 N. Icel. Grimsey (0. D.); Eyjafjöröur. 

 NW. Icel. Skâlholtsvfk. 

 SW. Icel. Reykjavik. 

 S. Icel. Vestmannaeyjar. 



Fam. Ulotliricaceæ. 



Ulothrix consociata Wille Studien p. 25. 

 var. islandica no v. var. 



I have in several places met with a Ulothrix, which in company with 

 other algæ e. g. Ulothrix flacca, Godiolum and Urospora mirabilis forms 

 a matted growth on rocks at or above high-water mark. My specimens 



are all in dry condition 

 and their colour is light 

 green or light yellow - 

 green. The filaments are 

 not rarely adherent to 

 one another especially 

 in the lower part, and at 

 the base usually few or 

 many filaments coalesce. 

 The thickness of the fila- 

 ments varies from 10 { u 

 to 29 fi, but they are 

 usually 14 — 22 ^ thick. 

 The length of the cells I have found varying from about Vs to 2 k of the 

 breadth, and I have only occasionally seen cells, which were as long as 

 broad. The cell-walls are usually very thick, especially the outer walls, 



Fig. 5. Ulothrix consociata Wille var. islandica 

 nov. var. a, b, c (311 : 1) show the base of the fila- 

 ments with the rhizoids (compare the text); 

 cl (215 : 1) shows three filaments, which coalesce 

 at the base. 



