THE FRESH-WATER CYANOPHYCEÆ OF ICELAND 289 



Probably it is, however, an Ubiquist, but has frequently been ovcrlooked. 

 It grows in the mucilage of other algae, e. g. in Nostoc, Gloeocapsa and 

 Aphanothece. 



2. VAGINARIEÆ Gomont. 



VI. Schizothrix Kiitzing. 



Schizothrix calcicola (Ag.) Gom. 



Gomont, Monogr. I p. 307, pi. VIII, figs. 1 — 3. 



Oscillatoria sp. Liebm. 1841 p. 337? 



Oscillatoria rufescens Liebm. (,manu scriptum in Hcrb. Mus. Haun.)? 



N. Icel. Hrisey, hot spring over 40*^ C. (45'^?) ^/i 1898 (H. J.)! 

 — W. Icel. Deildartungahver. At the margin of the outlet, temp. 66" 

 ^/s 1914. — S. Icel. Reykjavik. Laugarne (Stp.)!? 



Area: Eur., Afr., As., Am. 



It is doubtful whether the specimen from Laugarne at Reykjavik, 

 which is the original of Liebman's short description cited above, really 

 is S. calcicola. The sheaths are not so distinct as they generally are in 

 this species, but rather much diffluent so that it attains a close resem- 

 blance to a Phormidhim. 



S. calcicola has generally been met with on walls (frequently in hot- 

 houses) and on rocks; but Tilden (1897 p. 194, pi. VIII, fig. 3) found it 

 at the hot springs in Yellowstone Park, and here it was one of the chief 

 algæ contributing to the formation of the remarkable alga-stalactites. 



Schizothrix lardacea (Cesati) Gom. 



Gomont, Monogr. I p. 311, pi. VIII, figs. 8-9. 



Hijpheothrix lateritia Rab. Alg. nr. 153. 



E. Icel. Hallormstaåir. Rocky chasm in the forest; on mosses and 

 on rock over which water was trickling. ^Vs 1914 (2 samples). 

 Area: Eur., As., Afr., Am., Alaska. 



On the above mentioned locality the species extended over rocks 

 and mosses in company with Tolijpothvix tennis and Mcsotaeniam sp. 

 The appearance of the thailus did not correspond with that described 

 by Gomont; it was not thick and stratified, but formed layers hardly 

 1 mm. thick over moss and rocky ground. Still. I consider the deter- 

 mination correct as the description of the threads and the trichomes 

 agree exactly, S. lardacea has been found on rocks and walls over which 

 water w^as trickling, i. e. just under similar conditions as the Icelandic 

 specimen. 



Schizothrix arenaria (Rerk.) Gom. 



Gomont, Monogr. 1 p. 312, pl. VIII, figs. 11-12. 



S. Icel. Geysi'r, Viti (Stp.) det. Gomont with the remark; Spec. man- 

 cum. — E. Icel. Vestdalur at Sey6isfj6r5ur. Rocky wall, forming dark 

 patches '*/7 1914. 



Area: Eur., Afr., Am., Austr., Spitzbergen. 



