795 



Lastly there are the more southern forms belonghig to group 

 IV. With the exception of some few species, especially those of 

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

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

 at Iceland; thus their north western boundary is at the Faeroes; in 

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



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

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

 the designations used in the preceding section. 



I. Arctic species: Ceratocolax Hartzii, Polysiphonia ardica, 



Criioria arctica, Monostroma groenlandicum; 4 species in all. 

 II. Subarctic species: 



Subdivision 1: Peyssonnelia Rosenvingii, Lithothamnion tophi- 

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

 Laminarice , Saccorhiza dermatodea, Acrochcete parasitica, Uro- 

 spora Hartzii and Chlorochyfriuin Schmitzii; 10 species in all. 

 Subdivision 2: Phaeostroma pustulosiim, Chlorochytrium derma- 

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



III. Cold-boreal species: Dilsea ediilis, Rhodochorton minutum, 

 Petrocelis Hennedyi, Rhododermis parasitica, Ectocar pus penicillatus, 

 Dictyosiphon Chordaria, Fucus serratus, Sphacelaria radicans, 

 S. olivacea, Codiolum Petrocelidis , Cladophora glaucescens and 

 Vaucheria sphcerospora; 12 species in all. 



IV. Warm-boreal 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 tliat 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 Fseroese 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 

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

 doubt that they are absent at the Faeroes. 



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

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



Botany of the Fieroes. 52 



