THE FHKSH-WATER CYANOPHYCEÆ OF ICELAND 301 



found by Esmarch (1914 p. 271) in vario?is earth-samples, and by Bristol 

 (1919) alive in more than 60 years old earth-samples. Hodgetts (1922 p. 20) 

 arrived at the conclusion that A. oscillarioides is a typical summer-form 

 and is apparently of the opinion that its vigorous development is due 

 to the high summer-temperature. Some of his own observations (p. 21), 

 however, seem to indicate that it maj^ just as well be due to the greater 

 intensity of the light during the summer. My own observations from 

 Iceland mentioned above seem to point in the same direction in that, 

 according to them, the development of the species is apparently but 

 slightly dependent upon the temperature of the water. 



Anabæna torulosa Lagerheim. 



Bornet et Flahault, Revision IV p. 236. Ostenfeld 1899 p. 241. 



S. Icel. Krisuvik. Outlet from the solfataras ^Ve 1896 C. H. O.)! 



The specimen has been determined by Johs. Schmidt. I have re- 

 examined it, but I have not been able to ascertain the correctness of 

 the determination with certainty. 



Area : Eur., S. Afr., Am. 



As the species lives by preference in brackish water the Icelandic 

 locality is slightly pcculiar. The water in the oullet from solfataras 

 is usually highly acid. Moreover, the species has been found by Esmarch 

 (1914 p. 270) in numerous earth-samples from Germany, even from at a 

 depth of 50 cm. 



III. Nodularia Merlens. 



Nodularia Hapveyana (Thwaites) Thur. 



Bornet et Hahault, Revision IV p. 243. Bornet et Thuret, Notes 

 algologiques II p. 122, tab. 29, figs. 14—16. 



E. Icel. Hvalnes. Mucilaginous masses; spring, nearly at highest 

 high-water mark ^Vs 1894 (H. J.)! — S. Icel. Knararnes Vs 1905 (H. J.)! 

 Einarsnes ^^8 1905 (H. J.)! 



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



The Icelandic localities are probably all situated close to the sea, 

 at piaces where the salt water presumably is able to assert itself. The 

 species has repeatedly been found on similar localities in other countries, 

 but it also occurs in i)ure fresh water and finally as a more or less 

 aérophilous alga on bark of trees and in earth. Esmarch (1911 p. -69), 

 e. g., found it in samples of cultivated soil from S. W. Africa, and B. 

 Muriel Bristol (1919 p. 97) in dried, up to 70 year's old earth-samples. 

 Its spores thus seem capable of retaining their power of germination 

 for a verv long time. 



■t) 



Nodularia spumigena Mert. 



Bornet et Flahault, Revision IV p. 245. 



S. Icel. Einarsnes ^^s 1905 (H. J.)! 

 Area: All continents, Antarctic. 



