40 THE DISTRIBUTION OF HEPATICZ IN SCOTLAND 
Madotheca Thuja. Subalpine birch-woods are frequent at 
the foot of corries from 500 ft. or 700 ft., extending to a 
limit of 1300-1400 ft., or rarely to 1700 ft. as in Choir 
Arder? Characteristic species are Sphenolobus ovatus on 
the trees, Anustrepta orcadensis on banks about the base 
of trees, with much Scapania gracilis and Leptocyphus 
Tuylori. 
On the slopes of the hills Anthelia julacea begins to 
occur in quantity on wet rocks and stony marshes at 800-— 
1200 ft. At 1700-2000 ft. on rocky ledges, among boulders 
and on rocky banks with long heather and Vaccinium, is 
the characteristic locality for the alpine or upper subalpine 
Atlantic species Jamiesoniella, Anastrophyllum, Mastigo- 
phora, Scapania ornithopodioides, S. nimbosa (rarely), 
with Plewrozia in a more luxuriant state than in the lower- 
lying peat-mosses. With these are associated quantities of 
Bazzunia tricrenatu and Herberta adunea. 
If the heather associates be taken as the limit of the 
subalpine region, as done by R. Smith in the Botanical 
Survey of the East Highlands, it may be considered to be 
at 1800 ft. alt. in the West Highlands. Above this, as is 
the case also in the alpine regions of the East Highlands, 
the characteristic species is Gymnomitrium concinnatwm 
on rocks, with G. obtusum, although the latter frequently 
occurs in quantity also below this altitude. In this 
region are also found Lophoziu alpestris, Haplozia cordi- 
folia, Seapania wuliginosa, Anthelia Juratzhkana, ete. 
Most of the highest hills have little soil near the summit. 
On Ben Nevis between 3600 ft. and 4400 ft. are found the 
high arctic-alpine species Gymnomitriwm varians, G. Crassi- 
folium, Marswpella nevicensis, Nardia Breidlerr, and 
Pleuroclada albescens in the small patches of moist soil 
which are scattered over the upper parts. 
HEBRIDES 
The hepatic flora of the Hebrides is similar to that of the 
mainland of the opposite west coast, when allowance is 
made for the comparative scarcity of sheltered ground in 
the former, and the barrenness towards the summits of the 
highest hills in the Inner Hebrides, also, to some extent, 
