THE BRYOPHYTA OF ICELAND r)39 



This specimen is not to be found in the collections ; on the other liand. 

 a specimen from Iceland, determined bj^ Morcb as Hijpimm arcticiinu 

 belongs to //. alp i mim. 



Rather common in N. and N\V. Iceland, where it grows on stoncs 

 in rivers, like the other species of Hijgrolu/pmim. It does not ascend 

 higher than about 200 metres above sea-level ; Isafjordur), and often 

 sets fruit which ripens in N. Iceland in the latter half of .luh'. 



Hypmim alpimim varies considerably in leaf-form, leaf-tissue and 

 habit. 



The leaves. which are most often spreading, are occasionally fal- 

 cato-secimd along the entire lengtb of the stem, in which feature it 

 approaches H. dilatatiim in habit. The Iceland specimens of H. alpinum 

 approach, on the whole, H. dilatatiim, both in habit, leaf form and struc- 

 ture of cell-tissue. The cells of the base of the leaves are often thickencd 

 and slightly porous. and the alar cells are sometimes colourless and 

 thin-walled, sometimes yellowish with slightly thickencd walls. The 

 leaf-form varies from almost orbicular to elliptic. The leaf-margin is 

 almost always finely toothed all round. 



I have, however, thought it more correct to refer all the Iceland 

 piants to H. alpinum, as at any rate the capsule and the perichætium 

 corresponded exactly to those in this species. Thus, fully developed 

 cilia have never been found in the peristome. The leaf-cells are also 

 shortcr than in H. dilatatiim and in size agree most nearly with those 

 in H. alpimim. 



310. Hypnum ochraceum Turn. 

 Amblystcginm ochraceum Lindb. 



Very common on stones in livers up to 300—400 metres above 

 sea-level, but only sterile specimens have been found. 



Varies considerably in size, habit. etc. 



Var. unrinatum Milde often occurs in company with the type. 



Var. filiforme Limpr. is rather common in swiftly flowing rivers, 

 where it often covers the bottom for long distances. 



Note. Ambliistegiiim polare Lindb. is rccorded by Gro ni und Tillæg 

 til Islands Kryptogamflora, Bot. Tids., 20, p. 1 13 to have been collected 

 near Vallancs by H.Jonsson. The specimen in c[uestion is in the 

 Botanical Museum in Copenhagen and is labelled ''Dichodontiiim pelln 

 cidiim, Pohjtrichiim alpimim, Amblijstegium polare, det. C. Jensen", but in 

 spite of a careful search it was not possible to find A. polare among 

 the specimens, so for the present the occurrence of this species in Ice- 

 land must be regarded as uncertain. 



311. Hypnum cordifolium Hedw. 



Amblijstegium cordifolium De Not. 



N. Iceland: Myvatn (Grl. !. NW. Iceland: Grunnavik!. fr. 

 This species is also recorded from the Olfusa, Nesland, Litlu Bor- 

 garkatlar and Thorodstadacngjar, but the piants from all these localitics 



35* 



