IV.— THE INVERTEBRATE FAUNA OF THE INLAND WATERS 

 OF SCOTLAND.— PART IV. By Thomas Scqtt, F.L.S. 



In this Report on the invertebrate fauna of the inland waters of 

 Scotland, I propose^ o describe, first, — the results of a partial examination 

 of Loch Tay in Pei^hshire ; and second, — the results of the examination 

 of tow-net gatherings and other material from certain Sutherlandshire 

 lochs, collected, and forwarded to Dr Fulton, the Superintendant of 

 Scientific Investigations, by W. S. Caine, Esq., M.P. 



1. — Loch Tay, Perthshire. 



Introductory. 



Loch Tay belongs to the Marquis of Breadalbane and is one of the best 

 salmon lochs in Britain. 



The district about Loch Tay is known to botanists throughout the 

 length and breadth of the land, as one of the richest in native alpine and 

 sub-alpine plants, in the British Islands ; some of the rarest of our native 

 ferns, mosses, lichens, as well as flowering plants, have been and may still 

 be obtained among the gullies and rocky crevices about the summits of 

 Ben Lawers and the neighbouring mountains, and every year people 

 interested not only in the British flora but in other departments of 

 natural history as well are frequent visitors in the district. 



Though Loch Tay and its surroundings are thus well known not only 

 to the mere pleasure seeker but also to the naturalist, no systematic 

 attempt has apparently been made hitherto to investigate the invertebrate 

 fauna of the loch, and the present contribution towards - that object may, 

 therefore, be of interest. 



It was during a short visit to the beautiful and picturesque village of 

 Kenmore, in September last year, that I had the privilege of making a 

 partial investigation of this fine Perthshire loch. Owing to the limited 

 time at my disposal I was only able to examine that portion of the east 

 end of the loch extending from the East Bay where the steam-boat wharf 

 is, westward to near Fernan. There are two islands at this end of the 

 loch — the ' Ministers Island ' — which is little more than a cairn of stones ; 

 and Aidan's Isle or the Isle of Loch Tay.' King Donald IV. was drowned 

 somewhere in the vicinity of Aidan's Isle ; and here Sibylla — Alexander's 

 Queen — died, and was buried a.d. 1122. 



Depth of Loch Tay. 



I was unable from want of time to take soundings of the loch, but the 

 following notes from a paper read at a meeting of the Royal Society of 

 Edinburgh, February 20th, 1888, by Mr James S. Grant Wilson of H.M. 

 Geological Survey, may not be out of place. Mr Wilson's paper 

 described the results of a recent bathymetrical survey of the chief 

 Perthshire lochs and their relation to the glaciation of the district, and 

 was illustrated by a carefully prepared chart of the various lochs referred 

 to.* In this paper Mr Wilson describes Loch Tay as being 14J miles in 

 length by about f of a mile in average width ; the surface level of the 



*This paper was published in the Scottish Geographical Magazine for May 1888. 



