442 A. HESSELBO 



and on scattered blocks of rock. It often forms there extensive, blackish- 

 green or almost black cushions, 2—3 cm. deep. 



In lava-fields it occurs associated wilh several other Alpine species 

 at the bottom of ravines, as on Reykjalieide (at an altitude of about 

 300 metres), in Thingvallahraun, where it was rather comnion on fallen 

 blocks in ravines (Gja), and ncar Hafnarfjordur, where it was also rather 

 frequent in lava-clefts. In Svinahraun it grew abundantly on damp 

 ground in a large depression at the edge of the lava-field. 



The leaves usually spread erectly, more rarely, for instance in piants 

 from Thingvellir, they are sccund. The fruit ripens almost at the same 

 time on mountain heights and in the lava-fields, viz. at the end of July. 

 Near Thingvellir it was found on July 29th with fully ripe capsules, 

 some of which had thrown off their lids. 



25. Dicranum Starckei Web. et Mohr. 



"In Islandia" (determined by Morch as Dicranum polycarpon). 



Widely distributed all over Iceland. 



This species is most widely distributed on damp gravelly flåts from 

 an altitude of about 400 metres upwards to the snow-line and is often 

 there, especially from about 400—600 metres, the most abundant constituent 

 of the vegetation, growing in extensive, continuous mats, 2—3 cm. deep. 

 It occurs however also on stones and damp rocks. It is found more 

 scantily in the more low-lying parts of the country, although, especially 

 in NW. and N. Iceland, it is frequent, mixed with other mosses, on 

 gravelly ground by streams. In the southern part of the country it 

 does not appear to descend to a lower level than 300—400 metres. 



Like Dicranum Blyttii this species grows also in lava-clefts, and it 

 was common on fallen blocks bolh near Hafnarfjordur and Thingvellir. 

 The piants from these localities were often 5—6 cm. high, with longer 

 leaves, in which feature they approached very closely to D. molle. 



The direction of the leaves varies considerably, orthophyllous forms 

 are the most frequent, especially on the ground; highly drepanophyllous 

 forms occur more particularly in drier localities, for instance on rocks. 



Fruit is almost always present. The majority of the specimens 

 collected (June— July) had old, emptj' capsules, and also young green 

 ones or half-ripe ones which probably ripen late in the summer. 



26. Dicranum molle Wils. 

 D. arcticum Schimp. D. glaciale Berggr. 



E. Iceland; Sej'disfjordur!, at an altitude of about 200 metres. N. 

 Iceland: Akureyri!. NW. Iceland; Dyrafjordur !; Sugandafjordur !; Isa- 

 fjordur!; KaldalonI; Dynjandi!. W. Iceland: Snæfellsnes, Mafahlid (H. J.)!, 

 at an altitude of about 300 metres; Budahraun (H. J.)!; Dalasysla, Vig- 

 holsstadir (H. J.)!, 550 metres alt.; Olafsvig (Morch)!; Svinaskard (F.)!; 

 Esja, Modruvellir!. at an altitude of about 450 metres; Hafnarfjordur!. 

 S. Iceland ; Thingvallahraun !. 



This species is also recorded from several localities by Gro ni und, 



