998 Proceedings of Royal Society of Edinburgh. [sess. 
encounter in places, where the canal has been made through 
small and shallow lochs, a very abundant aquatic flora. The 
submerged sides of the canal are also well clothed. All the plants, 
however, are those quite common to the waters of the district, 
and call for no special comment except at Coiltry Loch, which in 
parts is simply filled with five dominant plants, viz., Lobelia 
Dortmanna, Isoetes lacustris, Littorella lacustris, Juncus fluitans, 
and Callitriche hamulata. The river Oich is a rather large- 
stream. Fig. 39 is from a photograph taken near Coiltry; its> 
bank here is, covered with Juncus eflusus. 
Loch Oich is the highest of the lakes in the Great Glen ; it i& 
about 4 miles long, with shores and islands abundantly wooded. 
Set amongst lofty and rugged mountains, it presents a magnificent 
piece of highland scenery (fig. 40). The aquatic flora is similar to- 
Loch Ness. Over a great area of this loch the water is shallow, 
the bottom being well within the photic zone, and aquatic 
vegetation fairly abundant, but of restricted variety. The water 
is peaty, very similar to that of Loch Ness. Littorella lacustris. 
Lobelia Dortmanna, and Isoetes lacustris are extremely abundant 
and form a dense bottom carpet; Juncus fluitans, Callitriche 
hamulata, Myriophyllum alterniflorum, Fontinalis antipyretica, 
Glyceria fluitans, Utricularia vulgaris, Carex rostrata, C. aquatilis, 
all very abundant and dominant ; Equisetum limosum, scarce and’ 
plants small; Potamogetons scarce, except natans and lucens; 
Characese are also scarce. The shores of this loch are stony or 
sandy, with very sparse vegetation or none whatever. Not- 
withstanding the innumerable small bays and shallow shores, 
there is very little marsh, so that plants of this habitat are not 
abundant. The Calder burn has brought down a great amount 
of detrital matter into the loch, forming large gravel banks ; but 
these are almost destitute of plants. The paucity of shallow water 
and marsh vegetation must, I think, be due to the abundance of 
stones and sand and scarcity of mud. The hills hereabout are 
faced with glacial drift gravel (fig. 42), which is brought into 
the loch by the burns (fig. 41). Nothing can be more antagonistic- 
to littoral phanerogams than gravel, shifting under the power of 
the waves. These long narrow lochs running in the direction! 
of the prevailing winds always have barren shores, owing to the- 
