50O CARL SKOTTSBERG 



Dichelachne schtrea-JMicrolepia strigosa Ass. 



F3 Dichelachne sciurea, 3 Hypochoeris radicata, i 



F2 Microlepia stjigosa, 3 Sonchus oleraceus, i 



Polypodium pJiymatodes, 2 Verbena litoralis, i 



Cy perns poly stachyus, i, rare Fi Calystegia sepium f:a, i 

 Doodia pasc halts, i, rare Dryopteris E spina sat, i, ge- 



Dryopteris parasitica, i nerally under stones. 



Elaphoglossinii taJiitense, \, G Cryptogams not collected, 

 gregarious 



Vittaria elojigata-yioss. Ass. 



Fi Vittaria elongata, 2 



G Campylopus dicranodontioides, Papillaria pascuana. 



The lichens were not collected. 



The third large crater, Rano Raraku, is wide open and the soft tufa 

 forms a dry, sandy soil covered with Sporobohis-Ass. The rocks are devoid of 

 macroscopic vegetation, but on nodules of hard stone Buellia Glasiouana, B. 

 stellulata and Physcia picta (badly developed) were observed. 



THE CRATER LAKES 



Rano Kao, June 2j, ipij- 



The lake, almost circular in outline, measures between 600 and 700 m 

 across. Xo outlet is known. Its surface lies about iio m above sea level. 

 Its depth is not known but supposed to exceed 100 m. Round the edge is a zone 

 of shallow water filled by a matted, elastic network of Polygonum rhizomes, 

 across which a firmer reed zone is reached. Together they form the mar- 

 ginal swamp. The reed belt leads over to the peat bog, which is supra-aquatic. 

 Evidently this bog should be classed with the high-moor formation. No 

 Sphagnum has been found; the peat-forming moss is a species of Campylopus, 

 endemic in Easter Island. The surface of this bog looks flat but it is not 

 quite even. Drier, almost inconspicuously raised patches are found. The 

 bog forms a continuous cover over the lake, leaving only the margin free. It 

 is possible that the principal reason why there is open water round the margin 

 is the constant afflux of rain-water from the steep slopes. 



1. Outer swamp zone, 5 to 7 m wide. Polygonum acumiiiatum-Ass. Plate 32. 

 F3 Polygonum acuminatum, 5. 



2. Reed-swamp zone, of very variable width, sometimes much wider than 

 the pure Polygomim belt. Scirpus 7'iparius- Ass. Plate 30, 32. 



S Scirpus riparius var. paschalis, F2 Dryopteris gongylodes, 2 



3 to 4 m high, 5 Kyllijiga brevifolia, 2 



F3 Polygonum acuminatum, 5 G Campylopus hygrophilus, 5. 



