THE FRESH- WATER LOCHS OF SCOTLAND. 353 



The long stretch of alluvium along the Amhainn-an t-Sratha Mhoir 

 indicates that the lake has been silted up for about a mile above its 

 present western limit. 



Loch an Tachdaidh and an Gead Loch. These lochs lie in the 

 bottom of the valley drained by the Garbh-uisge at Pait, which flows 

 into Loch Monar, and are entirely surrounded by drift deposits of the 

 later glaciation. All the small projections into these lakes are due to 

 moraine heaps, arranged in such a way as to suggest that they are 

 probably the terminal moraines of a lobe of ice that moved westwards 

 towards the basin of the river Ling. 



Loch Calavie lies in one of the passes through which the ice escaped 

 westwards from the Moiiar area during the period of confluent glaciers. 

 Though immediately surrounded by moraines and peat, it is evidently 

 in part a rock basin, as the rocky barrier formed of muscovite-biotite 

 gneiss appears in the stream not far below the outlet of the lake. The 

 deepest sounding is 84 feet. 



Loch Bunacharan- and Loch a' Mhuilinn. These lakes are situated 

 in the valley of the Farrar about midway between Loch Monar and 

 Struy. Their long axes seem to coincide generally with the strike of 

 the crystalline schists. In the case of the former lake, its height above 

 sea-level is 366 feet, its greatest depth 113 feet, and the position of the 

 rocky barrier exposed in the stream about one-third of a mile below 

 the outlet is about 360 feet. The surface level of Loch a' Mhuilinn is 

 417 feet, and the deepest sounding is 94 feet, and as it discharges over 

 solid rock, it is evidently a small rock basin. There is a high terrace 

 round Loch a' Mhuilinn and 011 the south side of Loch Bunacharan at 

 a level of 440 feet. 



NOTES ON THE BIOLOGY OF THE LOCHS OF THE BEAULY BASIN. 

 By JAMES MURRAY. 



The lochs of Beauly valley were surveyed in late autumn, during 

 very severe weather, unfavourable for the study of biology. The lochs 

 in Glen Affric were visited in a time of heavy floods, which raised the 

 lochs several feet while we were working at them. Though the tow-nets 

 were used, there was almost nothing got in them. The lochs appeared 

 to be flushed and washed out by the spate, or else the animals had gone 

 down to quieter water. 



Throughout the rest of the basin there was great uniformity, the 

 ordinary universal limnetic Crustacea and Rotifers alone being present, 

 with little call for remark. There was an entire absence of all the 

 northern species of Diaptomus, and, although Desmids were fairly 

 abundant in most of the lochs, there were none of the western species. 



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