458 A. HESSEL150 



in the more low-lj'ing parts of the country, but mav. however, occasion- 

 ally be niet with upwards of 600 metres above sea-level. 



7(>. Schistidium apocarpum Br. eur. 

 Subsp. (iracile (Schwågr.) Loeske. 



Verj' common. 



One of the most frcquent mosses, and met with from tlie lowlands 

 up to mountain heights. It occurs, in numerous forms, both on dry 

 and on damp rocks, and on more or less damp gravelly soil. On gra- 

 vellj' flåts, especialh' above an altitude of about 300 metres, it often 

 forms extensive growths. It occurs also very abundantly on tufT-rocks 

 (for instance in Esja and below E3'jafjall in a low, reddish-brown 

 form. Fruit is always present. 



77. Schistidium apocarpum Br. eur. 

 Subsp. ronfertum (Funck) Dixon. 



E. Iceland: Hof!; Seydisfjordur !. X. Iceland: Husavik, at an alti- 

 tude of about 400 metres!; Reykjahlid!; bclween Hnausar and Lækjar- 

 niot!; Vidvik :P. Sofoniasson !, several piaces near Eyjafjordur O. D.)!. 



This form has its main distribution in N. Iceland, where it is 

 rather common; thus, near Reykjahlid it was found abundantly on lava- 

 blocks. It grows by preference on rather dry rock-faces, or upon 

 stones. and has been gathered evervwhere in fruit. 



78. Schistidium alpicola (Sw.) Lirapr. 

 Var. rivularin (Brid.) Wahlb. 



Ver3' common in E., N. and ^Y. Iceland, more rare in S. Iceland, 

 ^vhere it is absent from many localities. 



This species grows on stones and rock surfaces in rivers, often in 

 great abundance, covering the banks and the stones in the water for 

 long distances. It does not appear to ascend much higher than about 

 300—400 metres above sea-level. 



The chief reason for its occurring more scantily in South Iceland 

 must be sought in the faet that the w^ater in many rivers is turbid, 

 owing to the glacier-clay carried in them. In this part of Iceland it is 

 met with especially in rivers with clear water, at an altitude of 200 — 

 400 metres, more rarely in the low land. 



Var. etmljncola Loeske. Grimmia alpicola Swartz. 



N. Iceland: Dettifoss!, fr. 



This form, which in the above locality grew on blocks of basalt 

 at some distance from the waterfall, but nevertheless exposed to the 

 spray, appears to be as rare in Iceland as in most of the rest of 

 Elirope. Forms, intermediate between this form and var. riviilaris, have 

 not been collected. 



