THE FRESH-WATER CYANOPHYCEÆ OP ICELAND 271 



The form found in the three above-mentioned samples had very 

 small cells, ca. 2 /< or slightly larger. It consequently approaches C. mi- 

 niillssinuiin Lcmm. (1910 p. 81). The colonies, too, were slightly smaller 

 than in the typical C. Kiilzingianuin viz. ca. 26—28 jli. 



VII. Merismopedia Meyen. 



Merismopedia glauca (Ehr.) Niig. 



Niigeli, Gatt. einzell. Algen p. 55, tab. I D., fig. 1. Lemmermann 

 1910 p. 85. 



N. W. Icel. Botn in Geiii>j6fsfj6rc)ur, dried-up lake "g/t 1915 (H. 

 J.)! Same place, lake. -^/i 1915 (H. J.)! Arnarfjordur, Hariot (1893 

 p. 314), Belloc (1894 p. G). — S. Icel. Grimsta6ir, mud from "Floi" (2 

 samples) 30— ^1/7 1905 (H. J.)! Ibid. mud from dried-up bottom of a lake 

 in a "Floi" ^Vi 1905 (H. J.)! 



Area: Ubiquist. Lappland, Færoes, Novaya Semlya, Greenland. 



Not infrequently found in plankton, being, however, undoubtedly 

 a true bottom-form thriving best in mud on the bottom of lakes and 

 in streams with quiet water. It is capable of withstanding considerable 

 salinity of the water and exhibits.on the whole great power of adapta- 

 tion. According to Kolkwitz and Marsson (1908 p. 515) it should be 

 oligosaprobe. 



At all the above-mentioned Icelandic localities where I have had 

 opportunity to observe it, it occurred in mud in more or less dried-up lakes. 



Merismopedia tenuissima Lemm. 

 Lemmermann 1910 p. 85, p. 82 fig. 8. 



S. Icel. Grimsta^ir. Mud from dried-up lake bottom in a "Floi" 

 ^V^ 1905 (H. J.)! 



Area: Eur., As., Afr., Am., Antarctic, Færoes, Greenland. 



Occurs in the same piaces as the preceding species. 



2. CHAMÆSIPHONACEÆ. 



I. Clastidium Kirchner. 



Clastidium setigerum Kirchn. 



Lemmermann 1910 p. 97, p. 91 fig. 2. Hansgirg, Prodromus II 

 p. 125, fig. 38. 



S. Icel. Holmså, temp. 14 " ^Vs 1914, on Cladophora and Oedo- 



gonmm. 



Area: Germany, Bohemia, Courland, Lappland. 



In the above-mentioned sample I have only observed a few speci- 

 mens of this small rare species; but their appearance corresponded 

 exactly to the figures and descriptions quoted above. 



The species has hitherto been found like the species of Chamæsiphon 

 epiphytic on various algæ especially on the genus Cladophora. 



