420 A. HESSELBO 



C. bicuspidata and Cephaloziella Hampeana, woven into the tufts of 

 Sphagnum spp., but is as a rule sterile. 



Note. Cephalozia connivens is recorded by Morch and Gronlund 

 as found in Iceland, but all the specimens which have been investigated 

 belong to C. pleniceps. 



61. Cephalozia media Lindb. 



N. Iceland: Arnarfellsaurar (St.;!); NW. Iceland: Grunnavik!, inter- 

 mixed in tufts of Dicranum fuscescens. 



62. Pleuroclada albescens (Hook.) Spruce. 



E. Iceland: Seydisfjordur!, common above a height of about 400 

 metres N. Iceland: Akureyri!, common above 500 metres; Hestahraun 

 (St.)!. NW. Iceland: Very common above 300 metres!. Var. islandica 

 (Nees) Spruce. N. Iceland: Reykjaheidi!. S. Iceland: Thingvallahraun 

 ^Morch; Stp. ; Grl.;!); Hafnarfjordur !. 



The typical form is no doubt common on mountain heights, at 

 any rate in N., NW., and E. Iceland. In S. Iceland it has not yet been 

 found. On mountain heights it grows on stony flats associated with 

 Dicranum spp. (D. Starkei, D. molle and D. fuscescens), Lophozia spp. 

 and Cesia conclnnata or associated with Polytrichum sexangulare, Lophozia 

 ventricosa, Cesia concinnata, etc., on Salix-herbacea-Rats. 



The variety belongs especially to the lava-fields and grows there 

 at the bottom of deep clefts, creeping over blocks of lava, often in 

 abundance. It occurs there either in large whitish-green cushions or 

 mixed with Hylocomium spp., Rhacomitrium hypnoides, Polytrichum alpinum, 

 P. sexangulare, Lophozia spp., etc. Only sterile specimens of each form 

 have been found. 



63. Cephaloziella Hampeana (Nees) Schiffn. 



\ 7 ery common, but occurs only as scattered shoots intermixed in 

 the tufts of mosses, sometimes, however, also in tiny, yellowish-green, 

 brownish or reddish tufts upon these. 



It occurs on highly different substrata. On rocks and on earth it 

 grows in tufts of Dicranum spp., Ditrichum flexicaule, Distichium montannm, 

 Tortella fragilis, etc.; in bogs it has been found woven into tufts of 

 Sphagnum, Sphaerocephalus palustris, Hypnacece, Oncophorus spp. and 

 several others. Bog- forms, with elongated stems and widely spreading, 

 very much projecting leaves, agreeing most closely with var. erosa Warnst., 

 occur very commonly in Sphagnum cushions. 



The leaf-tissue varies very considerably, the leaf-cells, even on the 

 same plant, being sometimes quite thin-walled, sometimes more or less 

 thickened; the leaves also are more or less outspread, so that all pos- 

 sible transitional forms between this species and Cephaloziella rubella 

 are known. 



