236 THE FRESH-WATER LOCHS OF SCOTLAND 
of the loch, occupying large areas in sheltered bays. Such floating 
Algae are a constant feature in lowland lochs where the water is 
polluted with sewage. Many submersed plants had a deposit of 
calcium carbonate upon their leaves, particularly Myriophyllum 
spicatum. Fresh-water mussels occur in extraordinary abundance 
in various parts of this loch, some of the specimens measuring 
7 inches in length. The roots and rhizomes of numerous plants, 
especially Glyceria aquatica, were frequently found covered with the 
young of these molluscs. The shallow portions of the south end of 
the loch are being rapidly encroached upon by the marsh vegetation, 
if one may judge by the wide area of bog, which in turn is being 
converted into meadow-land by the accumulation of the remains of 
plants that grow there. It would be very instructive to have a series 
of exact measurements, from various lochs, extending over a 
number of years, in order to show the rate of this encroachment upon 
the water, together with the rate of conversion of the bog behind 
into terra firma. A feature of this loch is the vast quantity of 
Potamogeton Friesii that chokes the loch in some parts. A 
number of other rare plants occur in abundance, together with the 
more usual species, for a list of which the original paper may be 
consulted. 
Auchenreoch Loch is six miles north of Dalbeattie. It is a mile 
in length, with a maximum breadth of nearly one-third of a mile, and 
is surrounded by agricultural land. The water is clear and not 
peaty. The main road from Dumfries to Castle-Douglas adjoins the 
east shore of the loch throuo;hout its leno;th. At the north-east end 
there are associations of Scirpus lacustris standing out in the water ; 
nearer the shore a large area is covered with Fhragmites communis, 
behind which there is a marsh with the usual plants. These con- 
ditions extend for some distance down the loch towards the south- 
west end. At other places there is a narrow strip of stony shore with 
meadow beyond, or there is scarcely any shore, grass land coming 
down quite to the water. 
Milton Loch is about a mile east of the last-mentioned. It is 
about a mile long by half a mile wide, and is surrounded by agri- 
cultural land. The water is clear and not peaty. The shores are 
flat and stony, and merge imperceptibly into meadow or arable land, 
except where bordered by trees or public roads. There are no 
associations of marsh plants entering the loch ; such as occur are 
merely a few species as stragglers over the stony shore, Alisma 
ranunculoides being one of the most abundant. Chara fragilis, var. 
delicatula, and Chara aspera, var. subinermis, are abundant on the 
bottom of the loch. 
Lochrutton Loch 'is three miles east of Loch Milton, and is three- 
