132 Proceedings of the Royal Society of Edinburgh. [Sess. 
muddy sand, and nearly everywhere such shores are covered near the water 
with Cladophora flavescens, mixed with CEdogonium, Spirogyra, etc., and the 
same species float on the surface of the loch, occupying large areas in 
sheltered hays. 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. Reference has already been made to the large quantities of the 
fresh- water mussel found in various parts of this loch (p. 116). The 
roots and rhizomes of numerous plants, especially Glyceria aquatica, were 
frequently found covered with the young of this mollusc. The shallower 
portions at 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 encroachment upon the water, together with 
the rate of conversion of the bog behind into terra firma. The submerged 
plants of this loch are as follows : — Littorella lacustris, forming a bottom 
carpet in shallow places as usual ; Callitriche autumnalis, covering large areas 
of the bottom; Potamogeton Friesii in vast quantity, some parts of the 
loch being choked with it; Myriophyllum spicatum, Potamogeton prae- 
longus, and Nymphaea lutea were all very abundant, as well as the Algae 
previously mentioned ; Potamogeton lucens was less abundant, while P. 
natans, Castalia speciosa, and Ranunculus aquatilis were scarce. The 
littoral flora is more varied, and is composed of — Phragmites communis, 
Equisetum limosum, Glyceria aquatica (fig. 54), Typha latifolia, Carex 
rostrata, C. Goodenovii, Phalaris arundinacea, Menyanthes trifoliata, Poly- 
gonium amphibium, Heleocharis palustris, Deschampsia caespitosa, Juncus 
lamprocarpus, J. effusus, Sparganium ramosum, all of which form more or 
less pure associations on many parts of the shore. In other places the bog 
is covered with an association in which any of the above may occur, more 
or less, as subordinate members, mixed with some of the following : — Carex 
acutiformis, Bidens cernua, Rumex Hydrolapathum, Cicuta virosa (fig. 56), 
GCnanthe crocata, Carum verticillatum, Apium nodiflorum, Radicula palustris, 
R. pinnata, Valeriana officinalis, Senecio aquaticus, Plantago lanceolata, 
Ranunculus Lingua (fig. 55), R. Flammula, Stellaria palustris, Myosotis 
palustris, Comarum palustre, Caltha palustris, Mentha sativa, M. aquatica, 
Equisetum palustre, Spiraea Ulmaria, Galium palustre, etc. [Carex disticha 
and C. teretiuscula occur in marshy ground to the south of the loch. — 
J. M‘A.] Figs. 53 to 56 represent some of the features of this loch. 
