74 H. MØLHOLM HANSEN 
Subularia formation has been described above, the Ran. reptans for- 
mation under the flöi (p. 70). There seems, however, to be no little 
difference between the environment of these two formations. The 
Subularia formation is found where the motion of the water (tem- 
porarily or continually?) is so strong that it causes a shifting of the 
bottom material, in the Ran. reptans formation it is less strong and 
no shifting takes place. As the third link in the chain we have the 
foi; here the water is stagnant and the bottom covered with mosses. 
All three formations have but a small density of species and 
practically the same species group spectrum, a high E percentage 
and concentration in the central part of the spectrum. The biolo- 
gical spectrum is of special interest. In the Subularia formation Th 
are dominant, in the R. reptans formation H, and in the flöi G. 
The Koenigia flag and the flag mo represent the flag ve- 
getation proper. The circling results are tabulated in table 17A, 3—7. 
Nos. 3—5 show the composition of the vegetation on flag at 
Björk in the south country. The dominant species are in the first 
place Koenigia islandica and Sedum villosum. Further Agrostis alba 
and Juncus spp. abound, J. bufonius, J. triglumis, J. biglumis, Tri- 
glochin palustre, Polygonum viviparum, Equisetum arvense, Sagina 
nodosa, Minuartia verna, Cerastium alpinum, C. cespitosum, Des- 
champsia alpina, Festuca ovina, and Luzula spicata. The table 
gives more precise information as to the part played by the in- 
dividual species and the variation from locality to locality. Spora- 
dically a number of plants occur which mostly originate from the 
surrounding formations, jadar and mo. 
Nos. 6—7 represent the flag mo at Lækjamôt in the north 
country. The dominant species are practically the same here (though 
Juncus bufonius was absent in the north country), and the individual 
species occur with almost the same F.-percentage. An essential dif- 
ference between the flag mo and the Koenigia flag is due to the 
presence of a quantity of mo plants in the flag mo, thus especially 
Thalictrum alpinum, Rumex acelosa, Poa alpina and P. glauca, Par- 
nassia palustris, Armeria vulgaris, Carex capillaris, Silene acaulis and 
several others. Another marked difference between the flag mo 
and the Koenigia flag is the great number of little knolls found in 
the former. | 
The individual species are differently distributed over the sur- 
face, some species being associated with the clayey soil others with 
the knolls. On the clayey soil the vegetation is open, and here we 
