202 OLAF GALLOE 
Consequently, 3 sterile fruticose lichens, 4 foliaceous lichens (of 
which 1 sterile) and 3 crustaceous lichens (of which 1 sterile). 
In the districts around Myvatn about Hlidarfjall I noted similar 
Dryas-heaths covering large tracts alternating with bare sand. Here 
the characteristic plants were also Dryas (F °/o 100), Empetrum (F °/o 
100), Glumiflore (F °/o 100) and abundance of dwarf-birches (F °/o 70) 
and Vaccinium uliginosum (F °/o 50). What has been said above 
about the factors which conditioned the life of the lichens in the 
heaths near Einarstadir holds also good as regards these heaths. 
A fairly rich lichen-covering occurred (F °/o 100), viz. fruticose lichens 
(F °/o 100), foliaceous lichens (F °/o 50) and crustaceous lichens (F °/o 
90); but, as may be seen, the larger species preponderate slightly, 
perhaps in correlation with the fact that dwarf-birches are more 
dominant here and determine the character of the lichen-vegetation. 
The following species were found: — 
| 
1 mn 
9 3 = 
Sa | 98 | oe 2 2 
Se | 22 | Se |F%| £ 5 
DE HESS see 2 27 
x i 5 
KENIA EICHE. en. ee — 100 a. 
Alectaria,-ochroleuéas.: 2, sr. + 90 BE 
Thamnolaermicularisé.s "11-004 + 100 + 
Alertoria ‘nisricas . n hrs: + 60 + 
Gadonia wangiferina 2: 24 eh A. ei + 10 + 
CeTATIAPDIVARIS MERE ac Eee CEE — 30 — 
— 17 WASTAGE A SEN v2. oss, eet rec + 20 + 
Leranora tartare. jis sce slave 2 + 90 — 
Consequently, 5 fruticose lichens, 2 foliaceous lichens and 1 
crustaceous lichen. 
The species of lichens are not everywhere the same, but they 
do not vary greatly. In the neighbourhood of Myvatn I traversed 
large tracts of heath, still poorer in phanerogams, where the fre- 
quency-percentage of the lichens was very great (F °/o 100) and where 
the landscape displayed dark patches of blackish-brown lichens 
(Cetraria islandica, C. nigricans and C. corniculata). Here we might 
perhaps be justified in speaking of “lichen-heaths,” but I think that 
their contents of Dryas, F °/o 100, make such a name superfluous. 
