THE AÉRIAL ALGÆ OF ICELAND 437 



same tubular antheridium, so in this it resemblcs V. borealis. In Børge- 

 sen s fig. 3. however, it is distinctly sliowii Ihat the membrane of the 

 oospore is papillose whicli it should not bc in V. horealis. Thus Var. 

 islandica occupies an intermediate position between tbe two species. Un- 

 fortunately it proved impossible to procure material of this variety, so 

 that it has not been possible for nie to form any opinion of this form. 

 I have found V, borealis in two phices in Iceland, in both cases on a very 

 damp substratum, viz. on a rocky wall with an outlluw of water (Fljots- 

 dalur) and on very damp ground by Lagarfljot. It will hardly survive 

 any intense desiccation. The species has liitherto only lieen ]<no\vn from 

 Finland, but lately Strøm has found it in Lapland (1923, p. 457) and 

 Norway (1926, p. 171). 



Vaucheria hamata Walz. Walz 1866, p. 148, Taf. 12, lig. 12-16. 

 Heering 1907, p. 159. 



W. Icel. 307, 338 — S. Icel. 371, 386. 



This species is well known for its common occurrence on soil and 

 is probably distributed over the greater part of the globe. To the areas 

 mentioned by Heering (1. c.) I can add Jan Mayen (Ostenfeld- 

 Hansen 1897, p. 23 and Denmark (Boye Petersen 1915, p. 349). 

 Miss Bristol (1920, p. 46, 75) found it in a single sample of arable 

 soil which had been dried for 6^/2 weeks. The reason why she did not 

 lind it in more of the samples is no doubt that the cultivation method 

 employed has not been favourable to this species. The specimens that 

 appeared were of less vigorous growth than normal ones. 



In Iceland I have found it in 4 samples, two of which were from 

 soil without any great amount of moisture, viz. from a potalo field (^338) 

 and a sheep fold (307). The other two samples, on the other band, are 

 from damper piaces, viz. from the shore of Laugarvatn (371) and the 

 bed of Gljufurholtså. 



Vaucheria synandra Woronin. Heering 1907, p. 169. fig. 93. 

 Vestmannaej'jar 399, 410. 



This species, which has most frequently been observed on shores 

 at high water mark, was found somewhat farther away from the in- 

 fluence of salt water in the two samples mentioned above. One sample 

 was collected in a small cave formed by the action of the waves, now 

 situated abt. 20 m above the sea, the other on a rock below a bird- 

 clifT at a height of abt. 50 m. 



Vaucheria sphærospora Nordst. Heering 1907, p. 171, fig. 96. 

 W. Icel. 343. 



Helgi Jonsson mentions (1913, p. 5) that this species occurs as 

 small cushions on the littoral meadow at Borg, intcrmixed among the 

 other piants, but it plays no great part there, whereas it forms growths 

 on the clay flåts, partly naked and partly overgrown with scattered 

 Triglochin murilimiim, outside the meadow proper. 



The Botany of Iceland. Vol. II. 29 



