572 A. HESSELBO 



water in all Ihese latter springs is pure and free from sulphuret- 

 ted hydrogen. 



Near the springs around Reykholt the Bryophyte vegetation is 

 rather scanty, partly on account of the sulphuretted hydrogen, and 

 partly on account of the constant disturbances caused by the 

 Iraffic and the use of the hot water. Sphagnum is practically ab- 

 sent. Along the outlets of the springs liverworts grew almost ex- 

 clusively. Fossombronia and Blasia pusilla were very common, the 

 latter grew in the form of flattened rosettes. Haplozia crenulata 

 and Aliciilaria scalaris were also frequent. 



Around all the other springs in Reykholtdalur there was a 

 luxuriant vegetation of Sphagna. S. papillosum was especially do- 

 minant and occurred in very large cushions, often 20 — 25 cm. deep, 

 but besides this many other species were found either intermixed 

 or separately in yellow, greenish, red or brownish cushions. The 

 following species have been found on warm ground in Reykholt- 

 dalur: Sphagnum papillosum, S. cymbifolium, S. angustifolium, S. ru- 

 bellum, S. Warnstorffii and S. teres were all common, S. subnitens 

 (fr.), S. acutifolium, and S. Dusenii var. falcatum occurred only now 

 and then. 



The Sphagnum spp. grew partly as a belt along the outlets of 

 the springs, partly on the boggy ground over which the hot water 

 was flowing. Intermixed with these grew everywhere Hypnum 

 stramineum, and in many piaces Polytrichum commune with ripe 

 capsules. Near Snældubeinstadahver Odontoschisma Sphagni 

 was scantily woven into tufts of S.rubellum. 



The warm clayey flåts next to the water, and especially the 

 steep banks stretching down towards the outlets, were covered with 

 a dense carpet of mosses and liverworts, in which the latter were 

 usually in the majority. The bluegreen rosettes of Anthoceros were 

 found almost everj'where, usually together with Fossombronia, Blasia, 

 Alicularia scalaris and Haplozia crenulata. In such piaces Archidium 

 also often grew in great abundance. 



Grønlund records Ccdoscopium nigritum as occurring abundantly 

 around hot springs in Reykholtdalur, but he has confused it with 

 Archidium phascoides. Catoscopium is found only exceptionally, 

 and, as it were, accidentally on warm ground, sometimes in a 

 somewhat divergent, slightly tomentose form (var. Gronlundii C. J.). 



On warm boggy ground the Sphagnum carpet was often greatly 

 intermixed with, or partly replaced by, a Hypnum vegetation to- 



