8 THE DISTRIBUTION OF HEPATICZ IN SCOTLAND 
Diplophyllum albicans, and D. taxifoliwm, most of which 
are usually present. With these are seen a few species of 
laxer habit, growing among such mosses as Dicranwm 
falcatum, notably Lophozia alpestris, L. ventricosa, and 
L. Floerkii, also occasionally a still larger species of 
xerophytic type in Plilidium ciliare. 
This formation extends further down the northern and 
eastern sides of a mountain than down the southern or 
western, and especially in depressions where snow remains 
throughout part of the summer. On the summits of many 
of our highest hills the soil occurs only in patches, and on 
these patches hepatics are either dominant or are sub- 
ordinate to mosses. A larger number of our hills, however, 
especially in the Gabbro and Torridon Sandstone districts, 
are practically without vegetation on their summits. 
Occasionally the summits and dry exposed ridges have a 
moss formation owing to the dominance of Rhacomitrium 
lanuginosum. In this case hepatics are almost absent. 
On many hills of rather less elevation, especially in schistose 
districts, the soil is completely covered with grasses on the 
summit, this being a “closed” formation instead of the only 
partially covered soil of the “ fell-field.” 
On several of the hills on the western watershed of 
the Highlands between 1700 ft. and 2000 ft. alt. or 
sometimes slightly higher, there is an interesting associa- 
tion of species, mostly of the Atlantic type. These 
are Mastigophora Woodsii, Jamesoniella Carrington, 
Scapania ornithopodioides and more rarely S. nimbosa, 
Anastrophyllum Donianum, Herberta adunca, Anastrepta 
orcadensis, Plewrozia purpurea, and Bazzania tricrenata. 
This may be named the Mastigophora association. It is 
found on shady, somewhat moist ground, usually either on 
rock ledges, or between boulders in rough ground among 
grasses and scattered plants of Calluna or Vaccinium. 
Frequent associates in the latter habitat are Leptocyphus 
Taylor: and Scapania gracilis. 
Some associations of hepatics are mentioned in the sketch 
of the Provinces, and a list of the Sphagnum-moor or peat- 
moss species is given in the section dealing with Habitats ; 
but little has been done in Scotland among Bryophytes 
froin an ecological point of view, and the investigation is 
