228 OLAF GALL0K 



ture on the subject, I have not found any allusion made to anything 

 of the kind. 



d. Liparite. 



This rock is not widely distributed in Iceland, and therefore 

 plays a very inferior part in the physiognomy of the country. In 

 chemical respects it is of the same composition as granite, since it 

 is the corresponding volcanic rock. 



I have only had an opportunity of investigating its vegetation 

 in very few localities, viz., in HliQarfjall, near the farm Reykjahlifl, 

 close to MVvatn, and near Geysir. I am therefore not prepared to 

 state anything about the vegetation it supports, when it stands in 

 salt water, nor what the conditions on it may possibly be, when 

 we lind it as a lofty mountain. 



Near Geysir, on the mountain situated close to the spring itself, '" 

 I found a very scanty vegetation consisting of crustaceous lichens 

 (F % 100), a few foliaceous lichens (F o .'16) and a little moss (F % 

 16). The mountain was far from being covered, consequently, the 

 vegetation was desert-like, and all the specimens were small, and 

 only slightly developed. The following species were found : 



Lecanora pallescens, crustaceous lichen. 



varia 



Lecidea auriculata. 

 Sterile, undeterminable, 

 Rhizocarpon geographicum, 

 Gyrophora erosa, foliaceous lichen, 

 cylindrica, 



On Hlii\irfjall near MVvatn, at the base of a solitary mountain- 

 summit, which rises above the surrounding country, there is a 

 mighty talus of large fallen blocks, and of debris. Upon the blocks, 

 ;m<l upon the mountain itself, there occurred a scanty vegetation - 

 open and desert-like - - of various foliaceous and crustaceous lichens. 

 The following species were found: 



Lecanora polytropa, crustaceous lichen. 



Aspicilia) alpina, 



impavida, 

 Rhizocarpon geographicum, 



1'armelin lanata, I'oliaceous lichen, 

 flyrophora crosa. 



cylindrica. 



