1012 Proceedings of Royal Society of Edinburgh. [sess. 
rostrata and Phragmites communis in sheltered hays. The north- 
west shore is bare and stony. The south-west end has an 
extensive marsh, covered with Equisetum limosum and Carex 
rostrata, etc., presenting no unusual features. I have noticed 
where the country people have mentioned lochs as being poor for 
trout-fishing, that the water has generally been clear; such is the 
case here. 
Loch Ruthven is a fine sheet of water some 2 miles long 
and 700 feet above sea level. Its water is peaty. The east and 
west ends are silted up with sand, so that there is a considerable 
area of shallow water at both ends ; but more especially so at the 
east. The shores are frequently sandy, more so than is general ; 
they usually slope gradually, and vegetation is abundant. The 
shallow areas at each end of the loch are often densely carpeted 
with the ordinary plants. Utricularia vulgaris is extremely 
abundant at a depth of 5 to 10 feet: with this Utricularia, 
Hypnum scorpioides, app. var. miquelonense (p. 983) occurs in 
plenty, so also does Potamogeton pusillus and Chara fragilis, var. 
delicatula. The photic zone here does not extend beyond a depth 
of about 23 feet, owing to the dark colour of the water. I noticed 
that the water was much more turbid at the east than at the west 
end ; the probable reason for this is due to the shallow area at the 
west end being of much less extent than at the east end. The 
greatest depth and bulk of water being at the west end, the 
sediment at the bottom is below the influence of the waves. At 
the east, however, a large area is within this influence, and the 
sediment is easily raised. Moreover, for some days previous to 
my visit, there had been a stiff westerly breeze. I have not seen 
this phenomenon at any other lake in the Ness area. The 
character of the vegetation at the sandy flat at the east end is 
shown by fig. 78. At the north-east end of the loch a large bay 
is filled with Equisetum limosum ; its existence here is due to the 
shelter afforded by the wooded hill from the westerly winds. 
It is interesting to notice how abruptly they terminate beyond the 
protective influence of the point (figs. 79, 80). At the west end 
of the loch a large sandy flat of several acres’ extent is entirely 
covered with a Juncus effusus association (fig. 81). There are 
also at the west end large colonies of Phragmites communis and 
