THE BRYOPHYTA OF ICELAND 561 



phyUiim, Plagiochila asplenioides , Cephalozia bicnspidata and C. 

 Hampeana. The Iwo sedge bogs described above mav be regarded 

 as types, and bj^ (ar the greater majority of the sedge bogs have 

 very nearly the same vegetation. 



3. Breidabolstadr on Fljotshlid (S. Iceland). A flat, 

 boggy tract of meadow-land beneath the low mountain-slope, inler- 

 sected by ditches and, lowest of all, by a low dike in order to keep 

 the water-level at a suitable height. The ground was even, without 

 knolis, and covered by a vigorous vegetation of Carices, with a moss 

 carpet at the bottom. Occasionally there were also patches where 

 the moss-covering was dominant, and the species of Carex occurred 

 in this as scattered individuals. The species were comparatively 

 few in number and were usually dominant in spots. The most 

 frequent species were Philonotis fontana, Mniiim Seligeri, M. cincli- 

 dioides, Cinclidium stygium , Bryiini ventricosum and Acrocladium 

 cnspidatiim. Here and there patches occurred with a more mixed 

 vegetation, which, in addition to the piants mentioned above, con- 

 sisted of Hypmim revolvens, Meesea trichoides, Splachniim vasculosum, 

 Lophozia quinqnedentata, and perhaps of several other species. Here 

 and there were tnfts formed by Sphagnum ruhellum and 5. teres. 



A vegetation of about the same composition as that described 

 above is very commonly met with in South Iceland, where tracts 

 of meadow-land, by means of draining, irrigation or damming up, 

 are kept at about the same ground-water level during the whole 

 summer. The knolis disappear — or are not formed — and the 

 moss-covering becomes poorer in species. 



4. Ljosavatn in North Iceland. A rather large sedge 

 bog on very wet ground, on the slightly inclined slope of the moun- 

 tain. The moss-carpet was composed of Cinclidium stygium, Mnium 

 cinclidioides , M. Seligeri, Paludella squarrosa , Camptothecium nitens, 

 Hypmim spp., Philonotis fontana, Bryum ventricosum, Thuidium 

 lanatum, Lophozia Kunzeana and L. quinqnedentata. Sphagnum 

 ruhellum, S. teres, S. Warnstorffii and S. Girgensohnii occurred abun- 

 dantly in large tufts. In the wettest parts, where the water reached 

 above the surface, grew thick, extensive carpets of Hypnum exan- 

 nulatum, H. stramineum , H. sarmentosum , H. giganteum and H. Ri- 

 chardsonii, all in very vigorous development, and in fruit. The 

 Hypnaceæ sometimes grew intermixed, but usually they occurred 

 separately, and were only slightly mixed with olher Bryophyta and 

 Cyperaceæ. This formation corresponds undoubtedly with C. Jen- 



