456 A. HESSELBO 



68. Tortula obtusifolia Schleich. 



S. Iceland: Flokastagil on Fljotshlid!; Drangshlid!. 



This very rare species was found in both places in very small 

 cushions, only 56 mm. deep, with numerous capsules which were al- 

 most fully ripe in the latter half of June. In Flokastadagil it grew 

 here and there on fallen blocks, especially in small fissures on the 

 vertical rock-faces. Near Drangshlid it was found in small quantity on 

 the dry faces of tuff-rocks in company with Tortula mu rails, Grimmia 

 Doniana and Orthotrichum anomahim. 



69. Tortula muralis (L.) Hedw. 



S. Iceland: Vestmannaey !; Drangshlid!. 



The plant was found very scantily in both places on dry faces of 

 tuff-rocks. On Vestmannaey it grew on a rock-face with a southern ex- 

 posure, associated with Grimmia marlllma and Barbula cylindrical near 

 Drangshlid it grew in association with Grimmia Doniana and Tortula 

 obtusifolia. 



70. Tortula subulata (L.) Hedw. 



Commonly distributed over the whole of Iceland. 



The plant grows almost exclusively in the low land up to about 

 300 metres above sea-level, and only in quite a few localities in S. Ice- 

 land has it been found at a higher level, for instance near Barkastadr 

 at an altitude of 410 metres. It is most frequent in S. and E. Iceland; 

 in N. and NW. Iceland it is somewhat less common, but has never- 

 theless been collected from a great number of places. It usually grows 

 on a rather dry substratum, e. g. humus-covered rocks, in rock-clefts, on 

 dikes and on peat walls of houses, mostly associated with Bartramia 

 ityphylla, Pohlia cruda, Encalypta rhabdocarpa, Brachythecium albicans 

 and other species. Fruit, which is always present, ripens in the end of 

 June or in the beginning of July. 



71. Tortula mucronifolia Schwgr. 



Vestmannaey!. 



It occurs here in localities quite similar to those of Tortula subu- 

 lata, for instance on dikes, in sandy soil and on humus-covered rocks, 



V 



and appears to be as frequent as this. The fruit was not yet quite 

 ripe towards the middle of June. 



72. Tortula ruralis (L.) Ehrh. 

 Commonly distributed over the whole of Iceland. 



V 



Torinla ruralis is a decidedly xerophilous species, and has, there- 

 fore, its widest distribution in the driest parts of the country. In the 

 lava-fields in the interior, for instance around Mvvatn, it occurs abun- 

 dantly; in NW. Iceland it is also more frequent than in the other parts 



