THE AÉRIAL ALGÆ Ol ICELAXD 371 



Melosira granulata (Ehrb.) Halls. O. Muller 1904 p. 267. V. H. Syn. 

 PI. 87 ligs. 9—12. 



E. Icel. 123. 



Found only in one localily, and thc prcscnce of living specimens 

 was not proved. Is hardly a terrestrial species. 



Melosira islandica O. M. Ollo Muller 1906 p. 56, Tab. I. 



N. Icel. 252. 



Seen only in one sample from soil from the interior of Husavik. 

 Its occurrence here must presumably be due to an accident, all the speci- 

 mens being apparently dead. Not aerial. 



Melosira Roeseana Habh. Meister 1912 p. 40 Tab. I, ligs. 4— 5. 

 E. Icel. L. 68, 85, 99, 129 - N. Icel. L. 179, 184. 



This species is generally known to occur chiefly on damji rocks 

 with dripping water and in piaces where small streams frequenlly makc 

 their way down (West 1916 p. 423). I have likewise found il in simi- 

 lar piaces in E. Iceland, and in a couple of lava caves in \. Iceland. 

 In Ihese caves there is presumably some proteclion against strong dc- 

 siccalion, and il must be permissible to infer that it is a species which 

 on the one hånd requires strong aéralion to thrive well, but on the 

 other hånd will scarcely withsland any very intense desiccation. Ils 

 habitat would also seem to indicate that it hardly needs much organic 

 or particularly nitrogenous nourishment in order to thrive well. 



Melosira varians Ag. Meister 1912 p. 39, Tab. I, Hg. 1. 



N. Icel. L. 215. 



Found in a living state on mud in thc ravine »Stora Gja« east of 

 M.vvatn. This mud was quite salurated with water and since othcrwise 

 the form habilually occurs in water, among algæ and as a coating on 

 higher piants, slones, palings, etc. it most probably requires plenly of 

 moisture. Hence it can hardly be rcgarded as an aerial alga. 



PENNATÆ. 

 I. Meridioneæ. 



Meridion Ag. 

 Meridion circulare Ag. Meislcr 1912 p. 53, Tab. IV ligs. 2— 3. 

 E. Icel. 24, 25, 78, 85, 129 - N. Icel. 133, 161. 



Occurred in 7 of my samples, but I only saw dead frustules. As il 

 is a very common species in Iceland (Østrup 347 samples), I suppose 

 that its ])resence in my samples is due to accidental circumstances. and 

 it is undoubtedly no terrestrial Dialom. 



