THE BRYOFHYTA OF ICELAND 407 



where the plant has been found on other than warni ground is near 

 Thingvellir where it was growing in a ditch along the road to Hrafnagja, 

 on claj' washed together into a heap; there it had for companions 

 Dicranella crispa, Didynwdon nibeUiis, Eiicalyx siibellipticus and tiny 

 piants of Pohlia, Bryiim, etc. 



Fam. epigonantheæ. 



17. Gymnomitrium corallioides Nees. 



S. Iceland: Thingvellir (Stp.; Grl.;!); Seljaland (Stp.;!). SW. Iceland: 

 Reykjavik (Grl.;!); frequent in Esja!; Hafnarfjordur!. E. Iceland: frequent!. 

 N. Iceland: Akureyri!. 



Occurs rather commonly, but as a rule, not abundantly in SW., E. 

 and probably also N. Iceland; in N\V. Iceland it has not yet been found. 

 It usually grows on the top of blocks of basalt and lava in small greyish 

 cushions, and rarely on the dry gravelly soil of G/-mjmm-heaths. On 

 the heath in Seljaland it occurred on blocks of basalt up to a height 

 of about 400 metres; in Esja it has been found up to about 500 metres. 

 Only sterile speciniens have been found. 



18, Gymnomitrium concinnatum (Ligthf.) Corda. 



Commonly distribuled over the whole of Iceland. 



In the lowlands it is especially common in the lava-iields, where 

 it grows both on the top of blocks of rock and in crevices and caves, 

 generally mixed with other Hepaticæ such as Lophozia alpestris, L. qiiin- 

 quedentata and Pleiiroclada albescens v. islandica; but it is also frequently 

 met with in clefts uiixed with other Bryophyta and creeping over stones. 

 But it has its greatest distribution from about 300—400 metres upwards 

 towards the snow-line, where it grows both on more or less damp 

 ground and on rocks either in low, extcnsive cushions or mixed with 

 other Bryophyta such as Lophozia alpestris, L. ventricosa, Plcarockida 

 albescens, Dicraniim Blytlii and D. fiilvellnm , usuall}' also woven into 

 dense cushions of Coiiostomiim boreale. 



In NW. Iceland especially, where it is one of the most frequently 

 occurring Bryophyta, it grows on gravelly flåts on mountain heights in 

 extensivc carpets associated with Ånihelia niinilis, Aliciilaria minor, Poly- 

 tricham sexangiilare and the other above-mentioned Bryophyta. Near 

 Seljaland, at about 650 metres, it was growing in great masses on 

 weathered basalt rocks associated with Marsiipella emarginata. Poly- 

 trichum sexangiilare and Dicraniim Blyltii. 



Fruit not rare; it ripens, according to attitude, during June— July. 



19. Gymnomitrium varians (Lindb.) Schiffner. 



N\Y. Iceland: Dvrafjordur! (at an allitude of about 350 metres^ on 

 damp gravelly ground; Reykjaheidi, in a lava-cleft!. Near DVrafjordur it was 

 growing abundantly in low, blackish-brown mats associated with Anthelia 

 nivalis and Alicalaria minor on ground saturated with melting snow. 



