LICHENOLOGY OF ICELAND 195 
mountain, extensive flats covered with heaths, knolly grassland, 
bogs and Cyperacee bogs. 
The grass-flats contained a great quantity of lichens, very un- 
evenly distributed, but in great numbers and well-developed speci- 
mens. The following species were found: — 
Alectoria ochroleuca. Leeanora subfusca v. hypnorum. 
Cladonia turgida. — tartarea. 
Sphærophorus fragilis. Pertusaria oculata. 
Cetraria aculeata. Lecidea elæochroma v. muscorum. 
Peltigera aphtosa. Coenogonium ebeneum. 
— malacea. Sterile crustaceous lichens. 
The lichens occurred not only on the top of the knolls, but 
also on their sides. On the other hand, quite flat grass-areas (con- 
sisting of Nardus, Anthoxanthum and some Carex spp.) were quite 
devoid of lichens and very bright-green; they were probably too 
damp for lichens. 
The species which have hitherto been found in grass-areas are 
the following: — 
Alectoria ochroleuca (fruticose). Peltigera malacea (foliaceous). 
Cladonia turgida = Collema spp. — 
— pityrea — Dermatocarpon hepaticum — 
— uncialis — Coenogonium ebeneum 
— fimbriata — (crustaceous). 
Thamnolia vermicularis — Lecanora tartarea — 
Sphærophorus fragilis — — subfusca v. hypnorum 
Stereocaulon coralloides — (crustaceous). 
— tomentosum f. cam- Psoroma hypnorum — 
pestre (fruticose). Pertusaria oculata — 
— incrustatum — Lecidea eleochroma v. muscorum 
Cetraria aculeata — (erustaceous). 
Peltigera canina (foliaceous). Bacidia flavovirescens — 
— aphtosa = Sterile crustaceous lichens. 
~ 
Consequently, in all, 24 species: 11 fruticose lichens (46 °/o), 5 
foliaceous lichens (21 °/o) and 8 crustaceous lichens (33 °/o). 
Here, as in the case of the heath, is a want which has not 
yet been supplied; the mass-occurrence (given in weight) of the 
lichens has not been determined. Nor is the average frequency- 
number known, for reasons which have been mentioned above. It 
is therefore difficult to give any comparison between the lichen- 
vegetation of the grass-areas of Denmark and Iceland, as regards 
quantity, so far as this is manifested by mass-occurrence and fre- 
quency-number. As regards quality, i. e. with respect to growth-form 
and systematic species, a comparison can more easily be made. 
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