456 A. HESSELBO 



68. Tortula obtusifolia Schleich. 



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



This ver}' rare species was found in both piaces in verj' small 

 cushions, only 5—6 mm. deep, with numerous capsules which were al- 

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

 liere and there on fallen blocks, especiall}' in small fissures on the 

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

 the dry faces of tufT-rocks in conipany with Tortilla miiralis, Grimmia 

 Doniana and Urthutrichiim anomalnm. 



69. Tortula muralis (L.) Hechv. 



S. Iceland: Vestmannaey !; Dningshlid!. 



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

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

 posure, associated with Grimmia marilima and Barbula cylindrica; 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 attitude 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 piaces. It usually grows 

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

 dikes and on peat walls of houses, mostlj' associated with Bartramia 

 ilyj)hylla, Pohlia cruda, Encahjpla rhabdocarpa , Brachylhecium 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 sand}- soil and on humus-covered rocks, 

 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. 



Tortula 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 Myvatn , it occurs abun- 

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



