584 A. HESSELBO 



Mniam serratum Schrad. Reykholtdalur. 



Aulacomnium palustre (L.) Schwagr. Common, several places in 

 abundance. 



Philonotis fontana (L.) Brid. Very common, often in masses. 

 Catharinea undulata (L.) W. et M. Common. 

 Polytrichum commune L. Common. 



gracile Dicks. Reykholtdalur. 

 Thuidium delicatulum (L.) Mitten. Frequent. 

 Hypnum molluscum Hedw. Abundant near all the hot springs 

 in Reykholtdalur. 



Hypnum Lindbergii (Lindb.) Mitten. Common everywhere. 

 Hypnum revolvens Sw. Common near many springs, especially 

 in Reykholtdalur. 



Hypnum chrysophyllum Brid. Geysir. 

 sarmentosum Whlb. Geysir. 

 stramineum Dicks. Very common everywhere. 

 exannulatum Gumb. Reykholtdalur. 

 Acrocladium ciispidatum (L.) Lindb. Common. 

 Climacium dendroides(L.)W. & M. In many places, plentiful near 

 Geysir. 



Hylocomium squarrosum (L.) Br. eur. Common everywhere. 



proliferum (L.) Lindb. Common in Reykholtdalur. 

 parietinum (L.) Lindb. In several places plentiful. 



Besides the species mentioned in the above list, several other 

 species are, however, also found as more casual intermixtures in 

 the moss carpet, especially species from boggy soil and from grass- 

 land, for instance Rhacomitrium canescens, R. hypnoides and Hypnum 

 uncinatum. 



Mesophilous Bryophyte Formations. 



The Bryophyta, as a rule, play a less prominent part in the 

 plant-covering of soil of a middle degree of dampness, than in that 

 of wet soil, because in the former the higher plants find more 

 favourable conditions of life, and the Bryophyta are consequently 

 driven more into the background and occur only as ground vege- 

 tation between the higher plants. Several other conditions are, how- 

 ever, of essential importance in this connection, for instance con- 

 ditions pertaining to the light, the direction of the slope and the 

 snow 7 -covering. Bryophyta bear shade better than do the higher 



