THE BRYOPHYTA OV ICELAND 531 



287. Hypnum intermedium Lindb. 



Amblystegium intermedium Lindb. 



Tilis species is no doubt common, at least in N. Iceland. where it 

 occurs around Eyjafjordur up lo aboul 500— GOO metres above sea-level. 

 Onl}' sterile speciuiens have bcen found. 



288. Hypnum revolvens Snv. 



Ambhistccfiiim revolvens De Not. 



Very common over the whole of Iceland. 



One of the most frequent and abundantly occurring mosses, which 

 often forms the bulk of the vegetation in the bogs, both in the low 

 land and in the Alpine region where it is plenliful even at an altitude 

 of about 600 metres, for instance near Eyjafjordur. Fruit, which is 

 often present abundantly, ripens in the beginning of July. 



Hypnum revolvens is distinguished from //. intermedium only by the 

 faet of its being monoicous. Therefore, in cases of the frequently 

 occurring quite sterile piants, it is really impossible to decide whether 

 they belong to the one or to the olher species. This is especially true 

 of the vigorous, slightly branched aqualic forms, which had previously 

 been referred to Hijpnum Cossoni Schimp. Both H. revolvens and H. 

 intermedium form such Cossonf-forms, but as they are mostly quite sterile 

 it is impossible to determine them with any certainty. 



289. Hypnum uncinatum Hedw. 

 Amblystegium aduneum (L.) Lindb. 



Very common everywhere upwards to the limit of plant-growth. 



Var. ovthothecioides (Lindb. j. 



N. Iceland: Grimsey (O. D.)!. NW. Iceland: Arngardareyri!; Grun- 

 navik!. E. Iceland: Kirkjubol (H. J.)!. 



Hypnum uncinatum is one of the most common niosses and occurs 

 everywhere both on dry and on damp substrata, on earth, on rocks, 

 in bogs, etc; and often in such quantities that it is the most abundant 

 constituent of the moss-carpet. It varies exceedingly in size, habit and 

 colour. Hypnum orthothecioides cannot be maintained as species; in 

 addition to the forms found in the above-mentioned habitats, others 

 forming all possible transitions to the type have been found in niany 

 other localities. Fruit, which is rather common, ripens in the fh'st half 

 of .lu ly. 



290. Hypnum Sendtneri Schimp. 

 Amblystegium Sendtneri (Schimp.) De Not. 



N. Iceland: Helgavatnsfloi (Stp.)!. 



