132 Proceedings of the Royal Society of Edinburgh. [Sess. 



muddy sand, and nearl}" 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 bays. Such floating Algse 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 ah'eady 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 b}' 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 quantitj^ some parts of the 

 loch being choked with it ; Myriophyllum spicatum, Potamogeton prse- 

 longus, and Nymphaea lutea were all \Qvy 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. eftusus, 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), 

 (Enanthe 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. 



