88 
Proceedings of the Royal Society of Edinburgh. [Sess. 
Glyceria fluitans, Br. “I, II., Ill,” IV., V., VI., YII. Widely dis- 
tributed, but seldom occurring in great abundance (ante, fig. 95). 
Glyceria aquatica, Wahlb. V., YII. Seldom seen at the lochs, but 
occasionally it occurs in great abundance : instance Carlingwark 
Loch, Lindores Loch, and others (figs. 54, 83, etc.). 
Alopecurus geniculatus, L., is very abundant on the sandy-muddy 
shore of Town Loch, Dunfermline. 
Agrostis vulgaris, With., is very abundant at the same place as the 
last mentioned, and also at Lindores Loch. Small patches or isolated 
specimens of these two grasses, with other terrestrial species, are 
frequently found mixed with the semi-aquatic vegetation of the 
littoral. Frequently, too, the grass sward of a moor or meadow 
adjoining a loch enters the water, and, contrariwise, aquatics such as 
Littorella lacustris leave the water, and compete for terra firma 
against the land plants. Aquatic and terrestrial zones of vegetation 
in such cases are undeterminable. 
EQUISETACEiE. 
Equisetum limosum, L. “ I., II., III.,” IY., Y., VI., YII. This is another 
very abundant plant ; large associations occur at the margins of 
lochs of all descriptions. The var. fluviatile (L.) is sometimes found. 
Equisetum arvense, L. Occasionally found overgrowing sandy or 
stony shores, in which case, unless sheltered by other vegetation, it 
is always prostrate and dwarfed. 
Equisetum palustre, L. Occasionally found amongst the marsh 
vegetation of lowland lochs, and sometimes on sandy-muddy shores. 
In the last habitat it is always dwarfed and frequently prostrate. 
Sometimes this and the preceding plant grow together in a dwarfed 
and semi -prostrate condition as at Loch Leven, in which case the 
two species are difficult to distinguish from one another. These two 
species of Equisetum usually occur so sparsely as to be scarcely 
worth mentioning as constituents of a loch flora. 
MARSILEACE^E. 
Pilularia globuiifera, L. YI. Rare, but occasionally very abundant, 
at Loch Dernaglar for example (fig. 69). 
LYCOPODIACEiE. 
Isoetes lacustris, L. “ I.,” IY., V., YI. Very general in peaty lochs, 
but neither so abundant nor so variable in form as in Area I. 
