438 A. HESSELBO 



hinds and iij) to 500—600 metres above sca- level. Near Akureyri it 

 was found on a damp ilat at about 500 metres. Near Barkarstadr it 

 occiirred abundantly on boggy ground at about 530 metres, and near 

 Seljaland it was also frequent at an altitude of about 500 metres on a 

 moss-grown gravelly flat. Only sterile specimens have been found. 



Fam. DIGRANACEÆ. 



14. Oncophorus virens (Sw.) Brid. 



Vcry common on damp ground. It grows both on wet hunnis- 

 covered rocks and in bogs, and also on damp gravelly ground, somc- 

 times as unmixed tufts and sometimes mixed with other mosses; it is 

 of equal fre([uency at all altitndes as far upwards as 600—700 metres. 

 It often occurs in great quantities and usually fruits richly. In the 

 lower districts the fruit ripens about July Ist. In S. Iceland this 

 species is cither wanting or rare in the lowlands up to a height of 

 about 300 metres (it has not been found on Vestmannae}'), but from 

 this height up to the snow-line it occurs abundantl}' in bogs. 

 Var. serraftis I3r. eur. occurs occasionally on wet rocks. 



15. Oncophorus Wahlenbergii Brid. 



One of the most commonly occurring mosses; it is found every- 

 where in damp localities just like O. virens. It is very common espe- 

 cially in bogs, excej)t in S. Iceland where, like O. virens, it has its dis- 

 tribution from an attitude of 300 metres upwards. 



\ ar. ji coiHparf tis (Funch) Br. eur. E. Iceland: Skreiddal!; Seydisfjordur!. 

 It grcw .in both localities on knoils in bogs. 



Var. eloiifjafnin Hagen. W. Iceland: Nordredalur!. It grew there on 

 boggy ground in association y/ilh Sphcignnni teres, S. nibeUum and S. fini- 

 briatum in loose tufts about 6 cm. high. 



Although typically developed forms of Oncophorus Wahlenbergii and 

 O. virens differ so widely from each other that they are .not likeh' to 

 bc confused, yet so many transitional forms occur, especially in Alpine 

 habitats, that very often it is a matter of opinion to which species such 

 a form should be referred. On the same plant leaves maj' be found 

 which, as regards the cells of the leaf-base, resemblc sometimes O. 

 Wahlenbergii and sometimes O. virens; also the leaf-margin is more or 

 less rccurved or plane. 



16. Dicranella squarrosa (Starke) Schimp. 



E. Iceland: Seydisfjordur!; Skorastadr (H. J.)l. N. Iceland: Husavik!; 

 near Ej-jatjordur (O. D.;!), fr. ; Lækjarmot!. NW. Iceland : Very common!. 

 W. Iceland: Vogur (H.J.)!; Esja!; Reykholtdalur !. S. Iceland: Holt!. 



This plant grows almost always in water, especiallj' on inundated 

 gravell}' ground by streams, on stones and in moss bogs, more rarely 

 on wet marshy ground. In N\V. Iceland it is one of the mosses of 

 most frequent occurrence being found in abundance associated with 



