208 



21. Phormidium uncinatum (Ag.) Gom. 



Specimens collcctcd by Lyngbye: »in saxis maritimis aqua dulci 

 irrigatis ad Hojvig prope Thorshavn« and of Lyngbye (Hydrophyt. p. 88) 

 cailed Oscillatoria snbfiisca are according to Gonionrs determination this 

 species; the same is the case with specimens in Lyngbye's Herbarium 

 from Ej de (Ost.). 



22. P. autumnale (Ag.) Gom. ^ 



Lj^ngbye's Oscillaloria siibfiisca § atra (Hydrophyt. p. 88) collected : 

 »ad rupes inundatas declives prope Næs Osteroe Færoæ cæpiose«, is ac- 

 cording to Gomont's determination this species. 



23. Oscillatoria curviceps Ag. 

 Lat. =: 15 ^. 



Amongst Sphagnum collected by Ostenfeld at Trangisvaag (Syd.). 



24. O. limosa Ag. 

 Lat. = 33 i^. 



Found among other algæ, carpeting the ground at Trangisvaag (Syd.). 



25. O. tenuis Ag. 



Gliversrejn near Thorshavn (Str.); and in Plankton from Sorvaags- 

 vatn (Vaago); lake near Ejde (Ost.); and Sandsvatn (San do). 



With regard to the plant named Oscillatoria ochracea (Dillw:) Lyngb. 

 (Hydrophyt. p. 89), no specimens from the Færoes are to be found in 

 Lyngbye's Herbarium, Copenhagen, so I can form no opinion about it. 



Order IV. RIVULARIACEÆ. 



26. Dichothrix compacta (Ag.) Born. and Flah. 

 Lat. cell. = 6 — 8 fi. 



In gatherings from »Gjov« near Vestmanhavn (Str.) and in a rill at 

 the foot of Ornefjæld near Trangisvaag (Syd.) some small fragments of 

 a Rivnlariaceæ were found which I think may be referred to the above- 

 named species. The walls were thick and stratified, the cells almost 

 half as long as broad. 



A closer investigation of the algæ growing on humid rocks will doubtless 

 prove this species as well as others to be conimon. 



Order V. SIROSIPHONIACEÆ. 



27. Hapalosiphon pumilis (Kiitz.) Kirchn. 



Some fragments which appear to me to belong to this species were 

 found mixed with other algæ in a gathering from Sand (S an do). 



^ In »Danmarks blaagrønne Alger (Botanisk Tidsskrift. 22. 1899) Jo- 

 hannes Schmidt has united these two species under the name of Phormidium 

 autumnale (Ag.) Gement emend. and I quite agree with liim in this. 



