THE BRYOPHYTA OF ICELAND 451 



country, where it is common in many places and often occurs in 

 enormous quantities. Morch records that it grows in holes in the 

 lava. Near Kolvidarhol it was found everywhere on lull', from the 

 farm (at about 250 metres) up to about 450 metres above sea-level; it 

 was found in extensive mats , especially on the vertical or overhanging 

 sides of the tumbled-down blocks, and in the interior of holes and 

 clefts. It was most frequent on Fljotshlid and south of Eyjafjall. 

 There it was growing in many places on the vertical sides of tuff-rocks 

 in the ravines and on the fallen blocks, for instance in Flokastadagil 

 near Breidabolstadr it covered long stretches of the perpendicular sides 

 of a ravine, from a distance of a few cm. above the water-level of the 

 river upwards, with a dark-green closely adhering mat in which almost 

 no other mosses were intermixed. In this part of the country it has 

 only been met with up to about 100 metres above sea-level. Only ste- 

 rile specimens have been found. 



Bryoxiphium norvegicnm is the only Iceland moss which does not 

 occur on the European continent or in the British Isles. Outside Ice- 

 land it has only been known to occur in a few localities in North 

 America (Ohio, Kentucky and Wisconsin). 



FAM. POTTIACE.E. 



53. Pottia Heimii (Hedw.) Br. eur. 



Iceland (Morch)! 



E. Iceland: Hornafjordur!. N. Iceland: near Eyjafjordur (F.)!; 

 Saudanes (St.)!; Grimsey (O. D.)!. NW. Iceland: Armuli!. W. Iceland: 

 Reykjavik (Grl. ;!); Borgarnes!. S. Iceland: Vestmannaey!. 



This species grows on sandy or muddy soil near the sea, and is 

 probably commonly distributed along the whole coast in such localities. 

 Around Reykjavik, on Vestmannaey and near Hornafjordur it was com- 

 mon, and was frequently found also on soil-covered rocks and in rock- 

 clefts close to the sea. 



The fruit ripens about July 1st; on Grimsey the fruit was fully 

 ripe on July 14th, but the lids had not been thrown off. Near Armuli 

 it was hardly ripe during the first days of July. 



54, Pottia latifolia (Schwagr.) C. M. 



N. Iceland: Hof near Eyjafjordur (O. D.)!; Os (O. D.)!, with ripe 

 capsules on June 17th. 



Note. Pottia triincatnla and P. lanccnlata are enumerated in older 

 lists as found in Iceland, but no specimens of these species are to be 

 found in the collections, and their occurrence in Iceland is very im- 

 probable. 



55. Didomodon rubellus (Hoffm). Br. eur. 



Barbula rubella (Hoffm.) Mitten. 



Very common everywhere on a more or a less damp substratum, 

 in rock-clefts, on the ground, on rocks and gravelly soil by rivers, in 

 bogs, etc. It grows sometimes in unmixed tufts and sometimes inter- 



