996 Proceedings of Royal Society of Edinburgh. [sess.. 
only other object of botanical interest about the shores is an ash- 
tree with an enormous base near Borlum (fig. 31). This is caused- 
by a rotting of the duramen ; the disease probably induced by the 
wet habitat. A little beyond this tree we arrive at the place 
whence we set out on our tour of Loch Ness. 
Loch Uanagan is situated in the Great Glen, about a mile 
south-west of Fort- Augustus ; it is about half a mile long and is 
43 feet deep in its deepest part. Its shores enter the water at 
a gentle slope, are sandy or stony, and its water rather peaty. 
The inflowing burn at the south-west end has introduced a large 
amount of detrital matter into the loch ; a considerable area of 
shallow water thus formed is covered with vegetation (fig. 32). 
At the opposite end of the loch, although the water is shallow,, 
there is little vegetation, owing to the erosive power of the waves, 
caused by the prevailing westerly winds. The general features of 
the aquatic and marsh flora are similar to what is found in the 
shallow water and marshes of Loch Ness. Loch Uanagan differs, 
however, in certain respects. Here we have a colony of Scirpus 
lacustris growing in water 4-7 feet deep and from 2-5 feet above 
its surface (fig. 33). Peplis Portula occurs in wet places about 
the shore. There is also an abundant bottom carpet of Characese,, 
Chara fragilis, var. delicatula, from the margin to 10 feet deep, 
Chara fragilis, approaching var. delicatula, 6-20 feet deep, Nitella 
opaca, 10-30 feet deep. Potamogeton lucens is very abundant to 
15 feet deep. Sparganium natans grows very abundantly in 
places (fig. 34). The photic zone extends to about the same deptli 
as in Loch Ness. 
Standing by the railway at the south-west end of the loch, one 
obtains an excellent example of the gradual change from aquatic to' 
moorland vegetation, arranged in the following order (fig. 35). 
Out in the loch Scirpus lacustris ; then for some distance no vege- 
tation rises above the surface of the water ; this space is filled 
with various aquatics — Littorella lacustris, Lobelia Dortmanna, 
Potamogeton natans, P. lucens, Myriophyllum alterniflorum, 
Characese, etc. Then we have a great belt of Carex rostrata 
advancing into the loch ; these in the drier places are mixed with 
Carex vesicaria, nearer the shore C. aquatilis abounds. In 
still drier places numerous bog plants obtain, Juncus bufonius 
