THE FRESH-WATER CYANOPHYCEÆ OF ICELAXD 305 



scraped off the stone. The rocks were here but slightly damp. It has 

 generall}^ been found under similar condilions. It is recorded as calci- 

 vorous by E. Bachmann (.1915 p. 51). 



II. Tolypothrix Kiitzing. 



Tolypothrix distorta (Fl. dan.) Kiitz. 



Bornet et Fhihault, Revision III p. 119. Kiitzing, Tab. phyc. II, 

 tab. 33, fig. V. 



E. I c el. Arnkelsger6i -^/e 1894 (H. J.)! — N. Icel. Skutustaåir, 

 small pool into which a spring flows out, temp. 7** ^^/7 1914. 

 Area : All continents, Lappland, Alaska. 



In the sample from Arnkelsgeråi T. distorta occurred in company 

 with Zijijnema sp. and Tribonema sp. Presumabl}' it has then grown in 

 rather quiet water as is the habit of the species. For the rest, it is 

 hardh' possible to distinguish T. distorta from T. penicitlata (Ag.) Thuret, 

 as already pointed out by Lemmermann (1910 p. 23 and 218). 



Tolypothrix tenuis (Kiitz.) Johs. Schmidt emend. 

 Johs. Schmidt, Botanisk Tidsskr. vol. 22 p. 383. Bornet et Flahault, 

 Revision III p. 122. 



T. lanata ibidem p. 120. 



E. Icel. SeySisfjoråur -^6 1893 (H.J.)! Hallormsta6ir, at the margin 

 of a forest lake, temp. 20 ^ ^^/e 1914. Hallormsta()ir 'Vv 1893 (H.J.)! 

 Pond near Ålftatjorn, on decaying piants from the bottom ^/t 1914. 

 Hreidarstaåir, on leaves from the bottom of a pond, temp. 12° ^/i 1914. 

 — N. Icel. Halldorstac>ir at Laxa, in spring, temp. 9*^' ^V' 1914. Hii- 

 savik, lake; the algæ at the margin partly lying loose, partly attached 

 on piants in a small cove, temp. 12*^ ^''/t 1914. Grimstafiir, in pond 

 on deca3'ing piants -^/i 1914. — N. W. Icel. Reykjanes, hot spring (Isa- 

 fjar6ardjup) Dyrafjor(^ur, Hariot 1893 p. 315, Belloc 1894 p. 6. Brekku- 

 dal in Dyrafj6r6ur ^''/g 1896 (C. H. O.)! — W. Icel. Glammastaflavatn, 

 on stones at the shore, temp. 15*^ ^/s 1914. Modruvellir, eyjatjorn, 

 plankton net dragged through plant growth, temp. 15" ^/s 1914. — S. Icel. 

 Varmå in Olfiis at Reykir, temp. 17° ^^'8 1914. (4 samples). Mi6hus 

 (Torfavatn), in small bays at the lake-margin, floating as small balls 

 at the water's edge Vs 1905 (H.J.)! 



Area: Cosmopolite, Antarctic, Lappland, Novaya Zemlya, Færoes, 

 Greenland, Alaska. 



This species is one of the most common C3'anoph3'ceæ and has a 

 v^'orld-wide distribution. Its proper habitat is undoubtedlj' the littoral 

 region of the lakes where it forms thin coatings on stones and piants; 

 at times it form Ægagropila-formations (Ljungquist 1915 p. 11), attempts 

 of which are also known from Iceland (Mi6hus). Further it seems ca- 

 pable of thriving on land, on dripping rocks, among damp mosses, nay 

 even on earth (Esmarch 1914 p. 272). Finally it has been found in 

 various piaces in brackish water. 



