162 H. JONSSON 



If we now turn to the individual species which (besides those 

 already mentioned) are found in the one coastal district but are 

 absent from the other, and which are important as regards the 

 appearance of the vegetation, we see, as already mentioned, that 

 such species are few in E. Iceland and numerous in S. Iceland. 

 Some of these species have a fairly social growth without, however, 

 forming independent associations. In the following, only those 

 species are given which occur most abundantly. 



East Iceland. 

 Lithothamnion flavescens. 

 L. foecundum. 

 Laminaria nigripes. 

 Turnerella Pennyi. 

 Ptilota pectinata. 

 Peyssonellia Rosenvingii. 

 Goilodesme bulligera. 

 Ulothrix consociata var. islandica. 



South Iceland. 

 Lomentaria clavellosa. 

 Plocamium coccineum. 

 Ghantransia Alariae. 

 Callithamnion Arbuscula. 

 Plumaria elegans. 

 Ceramium acanthonotum. 

 C. rubrum. 

 Polysiphonia fastigiata. 



Rhododermis parasitica. 

 Cystoclonium purpurascens. 

 Ptilota plumosa. 

 Petrocelis Hennedyi. 

 Ectocarpus fasciculatus. 

 E. tomentosus. 

 Cladophora rupestris. 

 Enteromorpha Linza. 



It should moreover be noted that all the Ce/Y/m/iz/??-species are 

 absent from E. Iceland. In S. Iceland, besides those mentioned 

 above, Ceramium atlanticum occurs, and it will no doubt be possible 

 to find several more Ceramzum-species in S. Iceland. 



The Epiphytic Vegetation on Laminaria hyperborea, as 

 mentioned several times, is very luxuriant in S. and SW. Iceland; 

 in NW. and N. Iceland it must also be said to be fairly luxurianl, 

 but in E. Iceland it is quite infinitesimal in amount, which is pro- 

 bably connected w 7 ith the fact that Laminaria hyperborea is rare in 

 E. Iceland. 



The epiphytic vegetation on the stipes of Laminaria hyperborea 

 is very luxuriant and finely developed in S. Iceland. The following 

 from the Vestmannaeyjar are given as an example : dominantly 

 on the stipe of L. hyperborea occurred Rhodymenia palmata, Delesseria 

 alata and Plocamium coccineum; less abundantly than the three 

 above-mentioned species occurred Delesseria sanguinea, Lomentaria 

 clavellosa, Lomentaria rosea, Euthora cristata, Giqartina mamillosa, 

 Ahnfeltia plicata, Petrocelis Hennedyi, Dermatolithon macrocarpum and 



