LICHENOLOGY OF ICELAND 185 



for instance Holasandr (north of Myvatn), the '"Sanders" in the delta 

 of the Jokulsa (at the head of AxarfjorSr), and the dunes between 

 MVvatn and the Jokulsa. 



The first of these tracts (Holasandr) consists of black sand, in 

 which are numerous stones with worn edges. It is very poor in 

 vegetation; there occurred however, scattered uniformly over the 

 entire surface, some grass, in tufts, at stated intervals of about l /s 

 V-2 metre. All other kind of vegetation was absent, for instance 

 owing to the strong sand-drifts prevailing everywhere - - not a single 

 moss or lichen was found. 



As mentioned above, the stones were highly worn by the action 

 of sand, and bore no mosses and hardly any lichens; scarcely a 

 hundred out of the thousands of stones I passed by during a two- 

 hours' ride, bore any vegetation at all, and even that of these few 

 stones was extremely scanty. The following species were found : - 



Stereocaulon spp. (fruticose lichen). 

 Parmelia lanata (foliaceous lichen). 

 Gyrophora arctica 



erosa 

 Lecidea pantherina (crustaceous lichen). 



The dune terrain east of Myvatn bore in numerous places a 

 scattered vegetation of Ely inns arenarins, which looked very remark- 

 able against the dark background of black sand. Here also strong 

 sand-drifts prevailed, and the ground was, in consequence, quite 

 devoid of lichens. 



As regards their vegetation and other external conditions, the 

 blown-sand areas in the delta at the mouth of the Jokulsa, greatly 

 resemble, for instance, Holasandr. The sand, which is mixed with 

 stones with worn edges, drifts very much. In stormy weather it 

 was not possible for us to see even a few hundred metres in front 

 of us on account of the sand-clouds, which filled the air near the 

 ground. 



In this place, a little grass, some Silene acanlis, and a few 

 other phanerogams, formed an extremely poor and scattered vege- 

 tation. Mosses and lichens were totally absent, on account of the 

 drifting sand. 



Desert-like, clayey-flats with a poor or scattered vegetation, 

 have been described more fully by Jonsson from East Iceland, 

 Snaefellsnses and South Iceland. They are, however, frequently more 

 luxurious, and can bear a vegetation which forms a kind of transi- 



