LICHENOLOGY OF ICELAND 195 



mountain, extensive flats covered with heaths, knolly grassland, 

 bogs and Cyperacew 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. bypnorum. 

 Cladonia turgida. lartarea. 



Sphserophorus fragilis. Pertusaria oculata. 



Cetraria aculcata. Lecidea claeochroma 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 Nardns, Anthoxanthnm 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 hepaticurn 



uncialis Coenogonium ebeneum 

 fimbriata (crustaceous). 



Thamnolia vermicularis Leeanora tartarea 

 Sphrerophorus fragilis subfusca v. hypnorum 



Stereocaulon coralloides (crustaceous). 



tomentosum f. cam- Psoroma hypnorum 



pestre (fruticose). Pertusaria oculata 



incrustatum Lecidea elasochroma v. muscorum 

 Cetraria aculeata (crustaceous). 



Peltigera canina (foliaceous). Bacidia flavovirescens 



aphtosa Sterile crustaceous lichens. 



Consequently, in all, 24 species: 11 fruticose lichens (46 %>), 5 

 foliaceous lichens (21 %) 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. 



13* 



