THE FRESH-WATEll CYANOPHYCEÆ OF ICELAND 265 



This species is evidentl}' a form intermediate between the aérophi- 

 lous and the hydropliilous algae, in that it is often found among mosses 

 and on eartli or damp rocks, but not in dry piaces however. Thus 

 Coupin (1915 p. 52) also refers it to the terrestrial species. 



E. Acton C1914 p. 444) has examined its cytology as well as the 

 structure of its cell-wall. She stales that it consists of alternating layers 

 of pectose and chitin, whereas cellulose is lacking. On the Icelandic 

 specimens the darker layers coloured brownish with chlor-zinc-iodine, 

 whilst in Rab. Algen, Nr. 921 the reaction was much fainter. 



III. Aphanocapsa Nag. 



Aphanocapsa Elachista W. et G. S. West var. irregularis Boye P. 

 n. var. 



Strato irregulari, non libere natanti; cellulis magis confertis. Diam. 

 cell. 1—2 ,a. 



E. I c el. Stagnant water in a branch to Grimså, Vallanes, among 



Myriophyllum temp. 14*^ -^/e 1914. — N. Icel. Pond near Grimstaåir 

 (Myvatn)^20/.^ 14 



This new variety which is closely related to Å. E. var. conferta W. 

 et G. S. West (1912 p. 432, pi. 19 fig. 1) is distinguished especially from 

 the latter by its larger and more irregular colonies which are not 

 free-floating. 



IV. Gloeocapsa Kiitz. 



Gloeocapsa atrata Turp.i Kiitz. 



Kutzing Phj'c. germ. p. 151. Tab. phycol. I, tab. 21, fig. 4. Någeli 

 Gatt. einzell. Algen tab. I, fig. F. 1. Rabenhorst Algen Nr. 173. 



S. Icel. Hafnarfjor(iur Stp. ! 

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



Occurs on rocks. The sheath colours violet with chlor-zinc-iodine. 

 This reaction agrees with the Icelandic sample as well as with Rab. 

 Algen Nr. 173. On the other hånd, Rab. Alg. Nr. 1914 is, as already 

 mentioned by Brand 1900 p. 312, note)), a different form, according to 

 Brand a Gloeothece nipcstris. In this exsiccatum the sheaths do not 

 colour with chlor-zinc-iodine. 



Gloeocapsa rupestris Kutz. 



Kutzing Tab. phyc. tab. 22, fig. 2. Lemmermann 1910 p. 64. Raben- 

 horst Alg. Nr. 2030. 



E. Icel. On dripping rocks Fljotsdalur ^^6 14. Ekkjufell -/t 1914. 

 Area: Eur., Afr., Am., Lappland, Spitzbergen, Greenland. 



Chlor-zinc-iodine colours the sheath deep dark brown, almost black. 

 It is a pronounced aérophilous, petrophilous species. 



The Botany of Iceland. Vol. II. 18 



