222 OLAF GALLGE 
Lecidea pantherina. Lecidea elata. 
— cyanea. Rhizocarpon geographicum. 
— erratica. — geminatum. 
— speirea. Caloplaca vitellina. 
— lapicida. Physcia aipolia. 
== elæochroma. 
Occasionally there also occur mixed with the above: Racodium 
rupestre, Polyblastia hyperborea, Acarospora Heppü, À. fuscata, Catil- 
laria athallina and a few foliaceous lichens (Parmelia lanata, Gyro- 
phora cylindrica and G. erosa). 
This association grows from the coast — where it begins a 
short distance above the Verrucaria-belt — to far up the mountains, 
where it stops at the snow-line. As regards its luxuriancy at various 
heights above sea-level, very little is known, but it appears to be 
least developed at great altitudes. I myself had a distinct impres- 
sion of this for instance from my observations on the mountain 
Sulur near Eyjafjöröur and the mountains near Hüsavik (on the 
north coast), and H. Jonsson states the same as regards the con- 
ditions on Snæfellsnæs; he writes: “The same is the case with the 
crustaceous lichens as with the phanerogams; they occurred ex- 
tremely sparsely on the stones in the upper part of the rocky flat.” 
The association is quite absent from the pebbles on the shore; it 
cannot endure inundation by salt water. 
The Staurothele-association occurs almost exclusively by 
waterfalls, where it forms black crusts on the rocks in all places 
where the spray from the falling water reaches. It is extremely 
characteristic of all such localities. Mixed among the slender, black 
thalli of Staurothele occur crust-like thalli of various Cyanophycee, 
so that it is often difficult to decide which of them is the more 
abundant. I have never found any other species of lichen directly 
connected with this association, which therefore contains only the 
one species Staurothele clopima. 
The Caloplaca-association (Placodium stramineum, P. alpho- 
placum and Caloplaca murorum), which on Bornholm (Denmark) 
is so common on the shore above the Verrucaria-belt, is very little 
developed in Iceland. I found only slight indications of it in Seydis- 
fjöröur. Helgi Jönsson records it from West Iceland. & 
The Verrucaria-association, formed by V. maura and an 
inconsiderable quantity of Lichina confinis, which is well-known 
from Bornholm and from all the other rocky coasts of the North, 
is also found in Iceland, where it borders the sea-shore from high- 
