THK HHYOPHYTA OF ICELAND 607 



Iceland, but tlie leasoii why in the following only Ihe Bryophyle 

 vegetation of South Iceland is mentioned, is because it is only this 

 part of Iceland that has been somewhat thoroughly investigatcd. 



Fljotshlid. North of the great river Markarlljot, the country 

 rises to a height of 200— (iOO metres. The slope stretching down- 

 wards to the Markarlljot is trenched bj'^ a great number of smaller 

 streams, many of which flow at the bottom of deep, narrow clefts 

 in the tulT-layers. 



One of the longest and deepest clefts is Bleiksagil near Bar- 

 karsladr (Fig. 81). This cleft has almost everywhere vertical or 

 overhanging sides, 100 or more metres in height, and is so narrow 

 at the top that in some piaces goats can jump across it. It is 

 therefore quite inaccessible for the greater part of its length, hcnce 

 only ils lower part has been investigaled. The sides were there 

 usually covered with enormous mats of mosses of which the prin- 

 cipal species were Hijpmim falcatuni , H. filicinuiu, H. moUnsciiin , 

 Brachijtheciiim riviilare and Philonotis fontana, all of which were 

 developed to an unusually luxuriant degree. H. falcatuni and H. 

 filicinum were in many piaces thickly covered wilh ripe capsules. 



In this moss carpet a great number of other Bryophyta were 

 found, partly intermixed wåth each other, partly in larger or smaller 

 tufts or growths. The following species were observed: Philonotis 

 tomentelia, Bnjum æneum, B. pallens, B. uentricosnm, B. inclinatum, 

 Mniol)rijnin albicans, Mninni serratum, M. punctatnni, Anomobryuin 

 filiforme, Encalypta ciliata, Didijmodon rubellus, Barbula cylindrica, 

 Distichiun} nwntanuin, Hynienostylium curvirostre, Anæctangium com- 

 pactum, Åmphidium Mougeottii, A. lapponicum, Haplozia riparia. H. 

 cordifolia, Lophozia quinquedentata. L. Miilleri, Scapania irrigua, 

 Blephorostoma trichophyllum, Madotheca Cordæana, Radula compla- 

 nata, Metzgeria furcata and Marchantia polymorpha. At the base 

 of the rock-side grew, among others, Mniuni undulatuni and Thui- 

 diuni taniariscinuni. At the extreme end of the cleft, where the sun 

 could shine on the rock faces, fruiting specimens of Preissia cominu- 

 tata often grew in abundance. The walls in the numerous caves 

 were often covered with Eurhynchium Sivartzii and Fegatella conica. 

 in Company with many, or a few, of the species found on the sides 

 of the cleft, which, however, on the whole, did not thrive w^ell in 

 the scanty light. In many piaces Fegatella formed also a belt along 

 the basal part of the rock-sides, especially where they projected. 

 On the roof of the caves Blepharostoma trichophyllum and Ambly- 



