of the Fishery Board for Scotland. 



243 



having been observed, yet it is almost certain that the more common 

 species of Pisidia and Limn&& will be found in the loch, — in fact it 

 would be rather interesting were it proved that no Mollusca existed in 

 Loch Scadowa, considering its comparatively large size and its suitability 

 as a habitat for such species. The Crustacea obtained in Loch Scadowa 

 comprised, besides the commonly distributed Gammarus (1) duabeni, eight 

 species of Copepoda, three species of Ostracoda, and nineteen species of 

 Cladocera. Notonectidae, Water-mites, Insect larvae, Diatoms, &c, were 

 also obtained in considerable abundance. Two of the species of Cladocera 

 appear to be undescribed — they are described and figured at the end of 

 the Keport on the Shetland Lochs under the names of Alona neglecta, n. 

 sp., and Alona rustica, n. sp. 



Loch Fada. 



Proceeding northward from Loch Scadowa, across the moor, I at length 

 reached Loch Fada. In this loch, or rather in some of its arms that 

 stretch for a greater or less distance up the hollows that branch off from 

 the general shore line, and where the water shallows much, aquatic vegeta- 

 tion was more abundant than it appeared to be in the other two lochs 

 visited. Yellow water-lilies just bursting into blossom filled up the 

 shallow bays, while Litorella formed a green spongy carpet that extended 

 up the almost level sandy beach to a considerable distance beyond the 

 edge of the water. In the more swampy parts the long trailing stems 

 of the Bog Bean formed an intricate net- work, from which arose at short 

 intervals the ternate leaves and beautiful feathery flowers so characteristic 

 of the plant. But this fine loch with all its floral beauty and apparent 

 suitability as a habitat for an abundant micro-fauna was, if one may 

 judge by the results of the examination of the gatherings collected here, 

 much less prolific in such organisms than either Loch Skealtar or Loch 

 Scadowa. 



Eighteen species of Crustacea were obtained in the gatherings from 

 Loch Fada, four of which were Copepoda, the other fourteen being 

 Cladocera ; neither Ostracoda nor Mollusca were observed, and this was 

 the only loch in the group of Hebridian Lochs now described in which 

 Camptocercus macrurus was obtained. The only effluent of Loch Fada 

 is a stream of clear pure water which flows from the east end down into 

 Loch an Aastrum, — a tidal loch much nearer Loch Maddy than this. On 

 making a partial examination of this stream (it is called the Fada Burn), 

 I found that Mollusca were, as regards numbers, well represented here, 

 though no specimens had been obtained in the loch itself. Three species, 

 — Pisidium yusillum^ Limnoea peregra and Ancylus fluviatilis, — appeared 

 to be of common occurrence, harbouring about the boulders in mid-stream. 

 These species are entered in the Table (Table I.) under Loch Fada. 



With the examination of Fada Burn my visit to Loch Maddy and the 

 North Uist Lochs came to a close. No attempt appears to have hitherto 

 been made to carry out a systematic investigation of the lochs of the Outer 

 Hebrides, and it is evident, from what has now been done, that such an 

 investigation might be expected to yield interesting results and extend 

 very considerably our knowledge of the fresh water invertebrate fauna of 

 our country. But this is a work that would require the services of 

 several students — each with a special knowledge of one or other of the 

 groups of organisms likely to be met with. 



Appended hereto is a Table (Table I.) in which will be found the names 

 of the species that have been obtained — and identified — in the lochs of 

 Barra and North Uist described in the preceding notes, and showing 

 their distribution in the various lochs. 



