737 



gans, Rhodochorton Rolhii, Pelvelia caiutlicuhtla, Ceramium (latntho- 

 notum, Prasiola crispa ■marina, Prasiola fiirfuracea and Prasiola slipi- 

 lata. There are moreover several littoral algse which grow but rarely 

 in littoral pools, and when found there, are only imperfectly devel- 

 oped. In littoral pools betw^een Thorshavn and Hojvig I have often 

 found e. g. Gigartina maiuillosa, which was hardly more than one 

 inch long. Species of Fiiciis, e. g. Fiiciis spiralis and Fiiciis in/latiis 

 become paler in the littoral pools, the thallus likewise becoming 

 thinner, and the plants are relatively small. This is the case with 

 several littoral algae. Evidently, some of them do not thrive when 

 they are constantly in water; it seems as if they require to be laid 

 bare for a shorter or longer space of time. Rosen vinge is also 

 very probably right, when he supposes (71, p. 191) that certain lit- 

 toral algae perform part of their work of assimilation at low^ tide. 



In the highest pools wdth their more or less fresh, luke-warm, 

 and often half polluted w^ater, where circumstances are very un- 

 favourable to the algae, only an Enteromorpha-xegeiskiion is found, 

 mainly consisting of forms of E. intestinalis. It is the only alga which 

 can live under such unfavourable circumstances. It may be found 

 far above the level of the sea, e. g. at Bosdalafos on Vaago where 

 it grows luxuriantly in small pools which are more or less inundated 

 by small fresh water streams. In this connection it may also be 

 mentioned, that I have found forms of Enteromorpha intestinalis at 

 a height of about 600 feet (cf. 7, p. 242—245 and 8, p. 492). 



A little lower, w^here the water is cleaner, other forms of En- 

 teromorpha occur, e. g. var. compressa^ var. prolifera and species of 

 Cladophora e. g. C. gracilis and C. sericea. Hildenhrandia gradually 

 gives a reddish hue to the sides of the pools, and several brown 

 algae appear, e. g. forms of Fucus spiralis and Fncus inflatus f. line- 

 aris; the latter has hitherto only been found at Famien on Sydero. 

 Forms of Ectocarpas litoralis, Scijtosij)hon lomentarius, Phyllitis fascia 

 and others moreover occur. Still farther dow^n, where the water 

 is regularly renewed at high tide, large, uneven brow^n crusts of 

 Ralfsia verrucosa are found intermingled with the red Hilden- 

 hrandia. The bottom may also be covered by a dense matting of 

 Corallina officinalis, sometimes mingled with Phijmatolithon poly- 

 morphum. On Corallina one may also find crusts of Dermatolithon 

 macrocarpum f. Corallince. Mingled wath Corallina, several dilTerent 

 algae may be found e. g. Dnmontia fdiformis, Rhodomela lijcopodi- 

 oides, Polysiphonia urceolata and P. Brodicei, Lomentaria clavellosa, 



