1020 Proceedings of Royal Society of Edinburgh. [sess. 
argillacea,* C. rostrata, Phragmites communis, Equisetum limosum, 
Chara aspera,* Enteromorpha intestinalis,* Spirogyra crassa,* 
lEdogonium capillare.* 
Vegetation here is in general more luxuriant than in the peaty 
lochs, and occurs all round the loch, more or less, and not 
particularly at the west side, as in the lochs of Area I. The flat, 
sandy-muddy shore, without vegetation, is shown in fig. 103 : in 
the winter this shore is covered with water. Typha latifolia is 
very luxuriant at Loch Loy (fig. 104). Loch Cran has a bottom 
carpet of Chara aspera and Potamogeton heterophyllus over the 
greater portion of it. Large associations of Carex rostrata are 
frequent. Being disappointed in the only available boat on the 
last-named loch, which could not be kept afloat for more than a 
few minutes at a time, I spent the remainder of a rather wet day 
on the Culbin sand-hills, and give herewith a short description of 
this interesting place. Behind the sand-hills a large belt of forest, 
chiefly Pinus sylvestris, has been planted in order to check the 
inroad of the sand over the land, and to reclaim from the dunes 
land already taken possession of by them. After one or more 
generations of the Pinus sylvestris have been cropped, the detritus, 
formed by the loppings and natural remains of the trees, together 
with that of such plants as associate with them, mixing with the 
sand, renders it fit for agricultural purposes or for the planting 
of a more valuable timber. The sand-hills here are of immense 
size, being amongst the largest in Britain. In places where the 
distance is shut out of view by dunes, nothing but an enormous 
tract of bare shifting sand can be seen, wearying the eye by its 
monotony. 
Hearer the forest, however, the sands are less shifting, and a 
vegetation is found encroaching over the dunes, partly of such 
plants as find their natural habitat thereon, as Ammophila arun- 
dinacea, etc. (fig. 105); and upon the border of the forest; plants 
also of the heath and moor formations, spreading gradually outwards 
over the sand-hills (fig. 106). 
A most interesting example in oecology is seen in the wonderful 
manner in which a trailing and straggling moor plant, Salix repens, 
adapts itself to the environmental conditions of the sand-dunes 
here. Instead of trailing, as amongst the heather, we find the 
