THE BRYOPHYTA OF ICELAND 561 



phyllum, Plagiochila asplenioides , Cephalozia bicuspidata and C. 

 Hampeana. The two sedge bogs described above may be regarded 

 as types, and by far 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, inter- 

 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 

 knolls, 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 , Mnhim Seligeri, M. cincli- 

 dioides, Cinclidium stygium , Bryum ventricosum and Acrocladium 

 cnspidatiim. Here and there patches occurred with a more mixed 

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

 sisted of Hypnum revolvens, Meesea trichoides, Splachnum vasciilosum, 

 Lophozia quinquedentata, and perhaps of several other species. Here 

 and there were tufts formed by Sphagnum rubellum and S. teres. 



A vegetation of about the same composition as that described 

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

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

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

 summer. The knolls 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 Cinclidinm stygium, Mnium 

 cinclidioides , M. Seligeri, Paludella sqnarrosa, Camptothecinm nitens, 

 Hypnum spp., Philonotis fontana, Bryum ventricosum, Thuidium 

 lanatum, Lophozia Kunzeana and L. quinquedentata. Sphagnum 

 rubellum, S. teres, S. Warnstorffii and 5. 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 . sti amineum , H. sarmentosum , H.giganteum and H. Ri- 

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

 Hypnacece sometimes grew intermixed, but usually they occurred 

 separately, and were only slightly mixed with other Bryophyta and 

 CyperaceaB. This formation corresponds undoubtedly with C.Jen- 



