795 



Laslly there are Ihe more southern forms belonging lo group 

 IV. With the exception of some few species, especially lliose ol" 

 which we know very little as to their distribution, we can in 

 general take it for granted , that tliey are most likely not found 

 at Iceland; thus their north western boundary is at the Færoes: in 

 Norway, however, several of them grow much farther north. 



As to the 33 species found at South -West Iceland, but not at 

 the Færoes, they can be divided into the following groups; I retain 

 the designations used in the preceding section. 



I. Arctic species: Ceratocolax Hartzii, Polysiphonia arctica, 



Criioria arctica, Monostroma groenlandiciim; 4 species in all. 

 II. Subarctic species: 



Subdivision 1 : Peyssonnelia Rosenvingii, Lithothamnion tophi- 

 phorme, Coilodesme buUigera, Ralfsia ovata, R. deusta, Myrionema 

 Laminariæ , Saccorhiza dermatodea, Acrochæte parasitica, Uro- 

 spora Hartzii and Chiorochytrium Schmitzii; 10 species in all. 

 Subdivision 2: Phaeostroma piistulosum, Chiorochytrium derma- 

 tocolax, C. Cohnii and Cladophora hirta; 4 species in all. 



III. Cold-boreal species: Dilsea edulis, Rhodochorton miniitum, 

 Petrocelis Hennedyi, Rhododermis parasitica, Ectocarpus penicillatiis, 

 Dictyosiphon Chordaria, Fiiciis serratus, Sphacelaria radicans, 

 S. olivacea, Codiohim Petrocelidis , Cladophora glaacescens and 

 Vaiicheria sphærospora; 12 species in all. 



IV. Wa r m - b o r e a 1 species: Bonnemaisonia asparagoides ; 1 species. 



Lastly we have the 2 new species: Rhodochorton repens and 

 Acrosiphonia flabelliformis , the distribution of which is unknown 

 outside of Iceland. 



Firstly as to Bonnemaisonia asparagoides, it must be pointed 

 out, that it is not perfectly certain that this species really grows on 

 the coasts of Iceland (compare Jonsson, 41 p. 141). 



Of the species mentioned in group III it is probable , that 

 some of them at any rate, especially the smaller species, will 

 also be found to grow at the Færoese coasts. With the exception 

 of some few species, there is, however, only a slight possibility that 

 some of the species belonging to group II should be found on the 

 Færoese coasts, and as to the 4 arctic species there is certainly no 

 doubt that they are absent at the Færoes. 



Thus we see that even if there is an important, though not 

 very great, difTerence between the flora of South -West Iceland and 



Botany of the Færoes. 51 



