300 



for comparison. These ponds are sitiiated aboiit 1200 metres above 

 sea-level, and diiring the summer the temperaliire may be as low 

 as 5,5^ C. and the warmest rarely more Ihan 12,5*' C. Otto 

 Mil 11 er has found 193 species, and 91 — e. g. about one half — 

 of them occur in the Færoes, constituting 34^ 7o of the entire number 

 of the Færoese species. Of the 130 more common Færoese species 

 57 — 44^/0 occur in Riesengebirge, but only 42 = 32% are common 

 in Riesengebirge, constituting 22 Vo of the species found in Riesen- 

 gebirge. This then shows that according to the percentage the 

 Færoese flora does not appear to be of particularly subalpine cha- 

 racter. If we now compare the genera which characterize both 

 localities then we shall arrive at the following conclusion: — 



Very common in the Færoes are: Synedra Ulna, Tabellaria 

 flocciilosa and Diatomn hiemale. Frequent are different forms of 

 Fragilaria, Tabellaria feiwstrata, Eunotieæ and Melosira (cremilata), 

 the latter generally occurs abundantly wherever it is found. Further 

 of Naincnlaceæ: FriistiiUa, Cijmbella, Gomphoncma, Anomoeoneis and 

 small Acbnanthes. Pinniilaria are rather frequently met with, but 

 seldom occur in considerable quantity in any of the gatherings. 

 Ceratoneis Arens and Rhopalodia gibba are both frequent. Of these 

 forms, characteristic of the Færoese material, Synedra is quite wanting 

 in Otto Miiller's list, Cymbella (excepting C. /^en/r/coso) are poorly 

 represented, Gomphonema, Achnanthes and Epithemia not common. 

 Tabellaria flocciilosa and Diatoma hiemale are frequent in gatherings 

 from two of the ponds; Fragilaria virescens and capiicina frequent, 

 also Snrirella and Anomoeoneis. Pinniilaria abundant. The most 

 characteristic dilTerence then is this, that Synedra, Gomphonema, 

 Cymbella and Achnanthes are, so to say, absent in Riesengebirge. 

 As, moreover, the remaining species do not correspond very closely 

 it cannot be said that the Diatom-flora of the Færoes taken as a 

 whole is subalpine. If on the other hånd we compare the Færoes 

 with Lule-Lappmark then the resemblance will prove to be greater. 

 In Lule-Lappmark the following genera are richly represented: 

 Pinniilaria, Frnshilia, Cymbella, Gomphonema, Eiinotia and Tabellaria. 

 These genera are also numerous in the Færoes, while Synedra 

 w^hich is extremely conspicuous here occurs only occasionally among 

 the Diatoms of Lule-Lappmark. A. Cleve mentions the following 

 genera as absent (o) or sparsely represented in Lule-Lappmark: 

 Amphora, Pleurosigma (o), Cocconeis, Rhoicosphenia (o), Snrirella, 

 Cymatopleura (o), Campylodiscus (o), Epithemia and Stephanodisciis. 



