THE AERIAL ALGÆ OF ICELAND 



377 



samples I found small specimens of the species, but in most cases I 

 could only lind empty frustules. There is reason to believe, however. that 

 the species is very widespread and frccpient on the giound in Iceland, 

 even though it hardly belongs to the species that withstand desiccalion 

 well. It occurred commonly in sample 70 from a mountain ravine with 

 trickling water in Hallormsta6 Wood, where it grew among Cyanophyceæ. 



Eunotia prærupta Ehrb. var. muscicola Boye P. 

 n. var. (Fig. 'S). 



Linea ventrali ad apices recta, in medio curvata, 

 valva long. 26,4//, lat. 6,8 /<, striis 11 in 10 // in medio, 

 15 in 10 fi ad apices. 



E. Icel. L. 123, 124, 128. 



This variety is especially remarkable b}'^ the form 

 of its ventral side, further it is about equally broad 

 throughout its whole length, so that the dorsal and 

 ventral sides have the same form. It is besides some- 

 what fmer-striated than the ordinary forms of E. præ- 

 rupta. I have therefore thought it right to describe it 

 as a special variety. 



In all three samples it was found among mosses. 



Fig. 3. Ennolict 

 pnvrupta Ehrb. 



V. muscicola 

 Bove P. n. var. 



"(X 1200) 



Eunotia prærupta Ehrb. var. bidens Grun. f. minor. V. Heurck Svnops. 

 PI. 34, fig. 22. A. Mayer 1918 p. 103. 



E. Icel. 77 - N. Icel. 256. 



I have only found this form in two samples, and in these only in 

 few specimens. 



Eunotia robusta Ralfs var. tetraodon Ralfs. A. Mayer 1918 p. 105; 

 V. H. Syn. PI. 33, fig. 11. 



E. Icel. 123 — N. Icel. 256. 

 Area : Eur. 



Only found in few specimens in the sami)les. Not previously found 

 in Iceland. 



Eunotia sudetica (O. Muller) Hustedt emend. A. Mayer 1918, p. 118, 

 Taf. II, fig. 52-53, 



S. Icel. 295. 

 Area: Eur. 



Only a single specimen observed in the sample. Not previously 

 found in Iceland. 



Eunotia triodon Ehr. V. Heurck Traité p. 303 PI. 9, fig. 383. 



N. Icel. 256. 



Onlj' a few specimens were found in the sample. It is hardly an 

 aerial species. 



