KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 20. N:0 5. ‘wy 4 
are of such a kind, The other families which are represented in the Flora of Scan- 
dinavia by only one species, are richer in species farther to the South, and may there- 
fore be supposed to have immigrated into the Scandinavian Flora from that direction. 
Table IV shows that the majority (54) of the 90 (92?) genera of the arctic Flora 
are represented by only one species; the greatest number of species possessed by any 
genus is 9 (Laminaria), and there are only few genera with any considerable number 
of species. Thus the average number of species in each genus becomes small, namely 
1,9. This is less than in the Flora of Scandinavia (2,3), of New-England (2,1), of Great 
Britain (3,5), of Cherbourg (2,4), and even less than in the Flora of the Norwegian 
Polar Sea (about 2,0). Among the genera of the arctic Flora the following are mono- 
typical: Polyides, Hamescharia, Hydrolapathum, Dumontia, FPurcellaria, Haplospora, Di- 
chloria, Isthmoplea, Gleothamnion, Diplonema, and Bulbocoleon; two of these are unknown 
without the arctic region. These circumstances, viz. the little number of species in the 
genera and the richness in monotypical genera, tend to prove the high age of the re- 
gion of the arctic Flora. 
The following species of the arctic Flora are common to all the three provinces 
of the region: 
Odonthalia dentata, Laminaria cuneifolia (?), 
Rhodomela lycopodioides, » nigripes, 
Polysiphonia arctica, Chordaria flagelliformis, 
Delesseria sinuosa, Elachista fucicola, 
Sarcophyllis arctica, Lithoderma fatiscens, 
Halosaccion ramentaceum, Chetopteris plumosa, 
Phyllophora interrupta, Sphacelaria arctica, 
Ahnfeltia plicata, Pylaiella litoralis, 
Fucus evanescens, Enteromorpha micrococca, 
Laminaria solidungula, Rhizoclonium pachydermum. 
Accordingly 19 or possibly 20 species, i. e. about 10 % of the total number of 
species in the whole region, about 15 % of that of the province of Spitzbergen, 70 % 
of that of the Siberian province, and about 16 % of that of the American province. 
A survey of the relation of the provinces to each other, with regard to the number of 
species, is exhibited in the following table. 
The province The American 
The Siberian province. 
of Spitzbergen. province. 
% of the % of the 6 of the 
Total number of | ‘Total number of ‘Total | number of 
number. |species of the| number. |species of the) number, |species of the 
e province, province. province, 
| | | 
Peculiar species ...22---.-.-...- Pes ee tastes Sauk. Dera Bl 39 % 4(3) | 15(11) # | 37 (88) | 32 % 
Species common with the province of Spitzbergen .... __... — —- 21 78 % 73 (77) 62 (66) 
» » with the Siberian province -............-.... 21 16 % = = 21 (22) 18 ¥ 
» » with the American province._............... 73 (78) 56 (60) % 21 (22) 78 : ie — 
