THE AÉRIAL ALGÆ OF ICELAND 375 



Synedra Ehib. 



Synedra Acus Kiitz. Meister 1912 p. 73, Taf. VI, fig. 23. 



E. Icel. 129. 



Occiirred in Ihe sample in a short form. It is iiardly an aerial 

 species, even though Østru]) has only found it in 3 samples from 

 fresh watcr. 



Synedra uina Ehrb. var. danica (Kutz.) Grun. Meister 1912, p. 72, 

 Taf. VII, fig. 3. 



E. Icel. L. 85. 



Like the preceding form, it is no aerial species. Østrup has it 

 from 148 samples from fresh water. 



IV. Eunotieæ. 



Eiinotia Ehrb. 



Eunotia diodon Ehrb. Maver 1918, p. 104, Taf. I, fig. 47— 51. 

 E. Icel. L. 128. 



In a preparation in water from the above-mentioned sample I found 

 a couple of specimens of this species with cell contents, whcreas I did 

 not find the species in the corresponding styrax preparation. In the 

 sample, which originated from cracl^s in a basalt wall. the Diatoms werc 

 found among mosses. 



Eunotia exigua (Bréb.) Rabenh. emend. v. genuina A. Maver. A. Mayer 

 1918 p. 113, Taf. II, figs. 16, 17. 



E. Icel.. 4, 123. 



This species is especially distinguished from E. palmlosa by being 

 still sienderer, and by the ends being strongly recurved. I have found 

 the following dimensions: L. 14-17,6/^, Br. 2,2-2,3 //. Str. 20— 23 in 10 /<. 



Found in mvri at a height of 300 m and among mosses on the 

 ground, in both piaces together with E. palndosa. Statcd by Østrup to 

 have been found by him in 1 sample. I also found this species in 

 several of the cultures from Mølholm-Hansen's samples of earth, 

 together with E. paludosa. 



Eunotia gracilis (Ehrb.) Rabenh. A. Mayer, Die bayer. Eun. 1918, 

 p. 110, Taf. II, lig. 15. V. Heurck, Traité p. 300, PI. 9, fig. 368. 



E. Icel. 24, 99, 125, 128, 129 - W. Icel. 321. 



Owing to the form of the cell, this species can as a rule only be 

 seen in zone-view. Hence a cerlain determination of it is difficult or 

 impossible. Only in sample 321 did I succeed in seeing it from the 

 valve face. According to the literature it has often l)een found on moun- 



25* 



