745 



in Greenland. It seems to me most likely that the somewhat dif- 

 ferent occurrence of these two species, also in the Færoes, may 

 be explained thus, that Finns nesicnlosns, as mentioned before, 

 re(|uires to be more sholtered than the other; therefore, this alga 

 in a somewhat exposed place grows facing landward and upper- 

 most, whilst it may grow nearer to tlie sea and farther down in a 

 locaUty as shehered as Vestmanhavn. 



Kig. 157. FiiciiK /ji//(i/;i.s association al a small, low-lying pool on tlie beacli. 

 Illustrations from rocky coast at Thorshavn. (F. B. phot.). 



Elachista fncicola is a very common epiphyte on Fncus vesicu- 

 losus, and Polysiphonia fastigiata is hardly ever sought in vain on 

 Ascophyllum nodosum. Besides these, other epiphytes are sometimes 

 found e. g. Ectocarpns litoralis, Edocarpus tomentosus, Ceramium 

 rnhrnm, Rhodymenia palmata etc. on both algæ. Below the dense 

 tiifts of seaweeds several red algæ are often found, e. g. Gigartina 

 mamillosa, Chondrns crispns, Hildenbrandia rosea, Rhodochorton 

 Rothii, etc. 



On a somewhat more exposed coast, Fucus vesicnlosns, as be- 

 fore mentioned, soon disappears and is replaced by Fucus spiralis 

 which forms an association at about the same height as Fucus 

 vesicnlosns, or a little higher. Below Ascophyllum nodosum, Fucus 



