THE BRYOPHYTA OF ICKLAND 535 



forms grow on rocks in and by the water, on wet rock-faces and on 

 the ground, both on wet gravelly ground and on the ground in bogs. 

 It often forms, especially in N. Iceland. an essential part of the moss- 

 carpet in bogs. It hardly ascends higher than about 300 metres above 

 sea-level. 5 piants are very common, ^ piants and fruit are far rarcr. 

 It has been found in fruit near Stafafell, Seydisfjordur, Hrutafjordur 

 and, rather frequently, in S. Iceland (both formsl. 



298. Hypnum molluscum Hedw. 

 Clenidiiim inollusciim (Hedw.) Schimp. 



Iceland (Morch)!; Bardshellir (Grl.)!; Brynjudalur Grl.)!. W. Iceland: 

 Common near the hot springs in Reykholtdalur!; BotnsdalurI; common 

 about Reykjavik!; common in Esja!; Kolvidarhol!, up to about 350 

 metres above sea-level. S. Iceland: Very common!. SE. Iceland: Horna- 

 fjordur!. 



This species is very common in S. Iceland. especially on Fljotshlid 

 and about Ejjafjall, but is also plentiful near Thingvellir, and frequent 

 in SW. Iceland as far as Borgarfjordur, where it is, however, chiefly 

 conflned to the warm ground. It appears to be quite absent from the 

 other parts of Iceland. 



H. nwUuscum grows on a damp substratum, both on damp rocks, 

 especially tuff, and on damp ground. Near Thingvellir it grew abundanth', 

 covering the blocks at the bottom of the large lava-clefts. Around the 

 hot springs in SW. and W. Iceland it occurs abundantly in several piaces. 

 Thus in Reykholtdalur it is one of the most frequent species of the 

 warm clayey flåts. 



It occurs almost exclusively in the low land, and only near Kolvi- 

 darhol was it found about 350 metres above sea-level. Only sterile 

 specimens have been found. 



299. Hypnum imponens Hedw. 

 Stereodon imponens Hedw.^ Brid. 



E. Iceland: Hof, on basalt rocks!. \V. Iceland: Esja!; Braudarholt '. 

 N. Iceland: Vidimyri, near a hot spring (Grl.)!. W. and SW. Iceland: 

 Near almost all the hot springs!. 



In SW. and W. Iceland it grew with a few exceptions on warm 

 ground. In Esja it grew in company with Camptothecium lutescens on 

 a grass-covered slope. and near Braudarholt intermixed with other 

 Hynaceæ on the top of knolls in bogs. 



On a warm substratum Hypnum imponens grows especially on the 

 drier clay-flats; there it often forms extensive mats, partly alone. partly 

 mixed with Hypnum stramineum, H. Lindbergii, H. molluscum, Hylocomium 

 squarrosum and other species. Only sterile specimens have been found. 



