72 



H. JONSSON 



If we compare S. Iceland and the Faeroes with regard to common 

 species, the following figures are obtained : — 



South Iceland 84 species 1 The Faeroes 157 species 



not common common not common 



10 (6%) 74 (44%) 83 (50%) 



Here it should be noted that S. Iceland is so very little known 

 that one is scarcely justified in comparing it with such a well in- 

 vestigated district as the Faeroes. Many of the species which in this 

 respect are peculiar to the Faeroes will certainly be found in S. 

 Iceland and, at any rate, 32 of them are known from other parts 

 of Iceland, principally from SW. Iceland. 



If we choose a larger district of the coast of Iceland, for in- 

 stance, the boreal district (S. Iceland and SW. Iceland) for compa- 

 rison with the Faeroes, the following figures will be obtained: — 



S. and SW. Iceland 126 species The Faeroes 157 species 



not common common not common 



25 (14%) 101 (55%) 56 (31%) 



On comparing Iceland with the Faeroes we obtain the following 

 figures: — 



Iceland 143 species 

 not common 



37 (19%) 



The Faeroes 157 species 

 common not common 



106 (55%) 51 (26%) 



The 37 species which grow in Iceland and are absent from 

 the Faeroes are the following: — 



fChantransia microscopica. 



Ceratocolax Hartzii. 



Turnerella Pennyi. 



Delesseria Baerii. 



Bonnemaisonia asparagoides. 2 



Polysiphonia arctica. 



Ceramium Deslongchampii. 



C. fruticulosum. 



C. circinnatum. 



C. arborescens. 

 fRhodochorton minutum. 

 fR. repens. 

 fDilsea edulis. 



fPetrocelis Hennedyi. 



Cruoria arctica. 

 fPeyssonellia Rosenvingii. 

 iRhododermis parasitica. 



Lithothamnion flavescens. 



L. foecundum. 

 fL. tophiforme. 

 fL. Ungeri. 

 fRalfsia ovata. 



R. deusta. 



fMyrionema Laminariae 

 tAscocyclus islandicus. 

 fEctocarpus penicillatus. 



1 These and the following figures apply to red and brown algae collectively. 



2 I attach no importance to the fact of this species having occurred in Ice- 

 land, as it has not yet been found again. 



