452 A. HESSELBO 



mixed with other mosses, and as a rule sets fruit, Nvhich ripens late in 

 August or early in September. It is most frequent in the low land up 

 to about 300 metres above sea-level, but is also met with, although 

 scantih', and often sterile, as far upwards as to the mountain lieights, 

 for instance on Isafjardarheidi, about 600 metres above sea-level. 



Forms which must be referred to var. hrevifolia Lindb. et Arnell 

 occur commonly together with transitional forms to the type. Near 

 Seydisfjordur the variet}' was found abundantly in reddish brown, dense 

 tufts, about 5 cm. high, in rock-fissures filled with soil. 



Note. Didijmodon tophaceus is recorded b}' Lindsa}^ from Ice- 

 land, but no specimens are in the collections and the record is pro- 

 babl}' due to an erroneous determination. 



56. Didymodon rufus Lorentz. 



E. Iceland: Stafafell!; Geithellir!. N. Iceland: Stadr near Hrutafjor- 

 dur!; Akureyri, at an attitude of 900 metres!. W. Iceland: Lundur! 

 Breidabolstadr in Reykholtdalur!. 



The plant, which was only found sterile, grew in all the above 

 localities in loose tufts, a few cm. high, on damp gravelly ground, as 

 a rule rather scantily. Near Akureyri it grew scantily among Sphæro- 

 cephahis turgidus and Rhacomitrium hypnoides. 



57. Leptodontium flexifolium (Dicks.) Hampe. 



N. Iceland: Grimsey (O. D.)! (f. compacta). 



Enumerated in Lindsay's list, but neither the name of the finder 

 nor Ihe habitat is given. 



58. Trichostomum littorale Mitten. 



Mollia littoralis (Mitten) Braithw. 



S. Iceland: Helgafell on Vestmannaey, on blocks of lava!; Hafnar- 

 fjordur, in a lava cave!; on warm clayey flåts near Reykjanes light- 

 house (Ostf.)!, associated with Preissia, Riccia and Archidiiim. 



59. Tortella inclinata (Hedw.) Limpr. 

 Mollia inclinata Hedw. Lindb. 

 E. Iceland: Vallanes (H. J. !. 



60. Tortella tortuosa (L.) Limpr. 



Mollia toiinosa (L.) Schranck. 



Very common all over Iceland. 



This species has its main distribution in the low land up to about 

 400 metres above sea-level. It appears to be rare everywhere at higher 

 levels, and hardly ascends higher than about 600 metres. ' It grows 



