288 Part III. — Twelfth Annual Report 



1 and is very pure and transparent. There are large quantities of fresh- 

 ' water shrimps (Gammarus pulex) all over the loch, — among the gravel, 

 ' under stones, and sticking to the weeds. Leeches are also very 

 1 abundant, but I do not find fly-life very plentiful. There are a great 

 ' quantity of curious gelatinous substances adhering to stones and lying 

 ' about in the gravel shoals which I never noticed before in any lake." 



The crustacean fauna of the little loch, to judge from the tow-net 

 gatherings sent to me, is evidently very abundant and very interesting. 

 One of the Copepods from this loch — Diaptomus serricornis — is new to 

 the British Islands. Since the discovery of Diaptomus serricornis, Lillje- 

 borg, in Loch Mullach Corrie it has been ascertained that the same species 

 was found by Mr David Robertson of Millport many years ago (1867) in 

 a pond near Lerwick, Shetland, but had remained unnoticed in print till the 

 discovery of the species in the Sutherlandshire loch. A variety of Daphnia 

 pulex (Linne), having the distal half of the hairs on the antennules and 

 also the posterior spine of a black colour, was frequent in the tow-net 

 gatherings from Loch Mullach Corrie ; I propose to call this variety 

 nigrispinosa. The 'shrimp' {Gammarus pulex, Linne) which Mr Caine 

 describes as abundant in the loch is an evidence of the purity of the water. 

 This is a species that can only thrive in water that is more or less pure ; 

 if transferred to impure water it very soon sickens and dies. The leeches, 

 referred to in the description of the loch, belong to the genus Heemopsis 

 (the horse-leech) which is found in ponds and ditches all over the country. 

 Seven stomachs of trout from this loch were sent by Mr Caine and they 

 all contained Gammarus in greater or fewer numbers, in one or two of 

 the stomachs there were along with the Gammarus a few insects, or 

 portions of insects, chiefly of the Phryganeidx. The plants that were for- 

 warded comprised specimens of a species of Chara ; of Fontinalis antipyre- 

 ica, — a moss common in some fresh-water streams and shallow lakes ; 

 of Littorella lacustris ; of Menyanthes trifoliata (the Bogbean) ; of 

 Millifolium spicatum (water-milfoil) ; and a species of Potamogeton, or 

 pond-weed. Among the animal organisms specimens of the curious 

 little so-called ' water-bears ' (Tardigrada) were observed specimens of 

 insects chieliy of the Phryganeidas and Coleoptera, specimens of the 

 Hamiopsis, already referred to, and the following Crustacea were also 

 obtained. 



Amphipoda, 



Gammarus pulex (Linn6). Abundant. 



Copepoda, 



Diaptomus serricornis, Lilljeborg. Frequent, 



Cyclops signatus, Koch. Few, 



j, thomasi, Forbes. Few. 



5, virides (Jurine). Few. 



j, wrmdatus, Fischer. Few,' 



„ tiffinis, G. 0. Sars. Few. 



Attheyellalcrassa (G. 0. Sars). Few, 



Cladooera. 



Daphnia pulex (Linn^). Frequent 



„ „ var. nigrispinosa, Frequent, 



Bosmina longirostris (Midler). Frequent, 



Alonopsis elongata, G. 0. Sars. Few. 



Alona quadrangularis (Muller). Few. 



Graptoleberisltestudinaria (Fischer), Few, 



Chydorus sphcericus (Muller). Frequent. 



