42 H. MØLHOLM HANSEN 
in the moss. Other species met with are especially Carex rigida, 
Polygonum viviparum, Silene acaulis, Armeria and Empetrum. Pro- 
ceeding still higher, Salix herbacea is the only more conspicuous 
phanerogam in the moss carpet. 
At its lower limit the mosathembur vegetation passes over into 
the Elyna mo. 
Above we have described the appearance and composition of 
the mosathembur vegetation on Lyngdalsheidi. If we enquire into 
its occurrence in other parts of Iceland, we find it described by 
Helgi Jönsson for East Iceland (1895, p. 70), for South Iceland 
(1905, pp. 40—42), and for Snæfellsnes (1900, p. 68 and p. 85). It is 
most abundantly developed in East Iceland where it covers large 
stretches of the mountain slopes in several of the fiords, and it is 
particularly well developed at high levels. In South and South-West 
Iceland it does not occur so plentifully, and apart from the lava 
fields, covers only small areas. Its appearance and composition, how- 
ever, are in close agreement in the various localities and correspond 
to what was given above for Lyngdalsheidi. 
In North Iceland and the highland tracts the mosathembur does 
not seem to occur as a stable typical vegetation. Ostenfeld does 
not refer to it in "Skildringer af Vegetationen i Island” III—IV 
(1905) either from Vestfirdir or from Melrakkasljetta. Personally I 
have looked for it in vain in Hüna Fléi, in the highlands at Arnar- 
vatnsheidi, and on Holtavöröuheidi. Typical mosathembur was not 
seen in any of these localities; it had been replaced by the melar 
vegetation. 
The moss mo observed by St. Stefansson on Grimstungnaheidi 
which “should most probably be understood as a transitional form 
between heather mo and pond vegetation’, the surface being uneven, 
more or less tufted, and the soil moist, at any rate in the first part 
of the summer, must not be confused with the mosathembur vege- 
tation which only occurs on the relatively dry stretches. Thus, 
the mosathembur vegetation in Iceland seems to be pe- 
culiar to the higher levels of the rainy and foggy east, 
south, and south-west country, that is to say, the coun- 
try south of the jökull line. North of this line, where the cli- 
mate is more continental, it does not occur as the typical vegetation, 
being replaced by the melar vegetation here. 
If we enquire into its distribution in the surrounding countries, 
we find it developed both to the north and to the south. Kolderup 
