32 BATYHMETRICAL SURVEY OF 



a few comparatively rare forms; very few molluscs were observed in 

 any of the gatherings.*" 



Twelve species of Entomostraca were captured by the tow-nets in 

 Loch Achray, Diaptomus, Daphnia, and Bosmina being taken in all the 

 gatherings. Holopedium, though common in September and June, was 

 not observed in November and March ; Bythotre plies also appears to 

 be subject to somewhat similar seasonal variation. Fifty species of 

 Entomostraca and four species of Mollusca were obtained by the 

 hand-net, and by dragging the tow-net for a short distance over the 

 bottom of Loch Achray. Three rare species : Diaptomus wierzejskii, 

 Lathonura rectirostris, and Monospilus dispar were obtained, and in 

 June a green fresh-water sponge (Spongilla fluviatilis) appeared to be 

 moderately common in some shallow parts of the loch.f 



Loch Vennachar contains a rich crustacean fauna, as well as other 

 invertebrates, most of which are suitable for fish food. Of forty-five 

 species of Crustacea recorded from Lochs Katrine, Achray, and Venna- 

 char, thirty-five species were observed in Loch Vennachar ; thirteen of 

 the species from Loch Vennachar were not observed in either Lochs 

 Katrine or Achray; fifteen of the species were common to the three 

 lochs. I 



Twenty-five species of Crustacea and four species of Mollusca are 

 recorded from Loch Lubnaig, including a new cladoceran (Alona 

 neglecta), and one or two species new to Britain. 



The following results were obtained by Mr. Scott in Loch Leven in 

 1890, 1897, and 1898. || 



In June, 1890, Mr. Scott found the fauna to be abundant and varied 

 Mollusca, Arthropoda, Annelida, and Protozoa being more or less 

 common all over the loch. Mollusca were common and generally dis- 

 tributed, except at that part of the loch called the " Shallows," the 

 bottom of which consists of little else than fine sand, and is therefore 

 not so suitable as a habitat for these organisms as where the bottom 

 consists of mud or vegetable debris. Fourteen species of Mollusca were 

 obtained, comprising five Lamellibranchs and nine Gasteropods. The 

 more common forms were Sphcerium corneum, Pisidium fontinale, 

 Valvatapiscinalis, and Planorbis cotitortus. The swan-mussel (Anodonta 

 cygncea) appeared also to be frequent. 



The Crustacea were by far the most numerous and varied of the 

 invertebrate fauna of the loch. Cladocera and Copepoda occurred 

 in great profusion all over and through the water. Daphnice, were 



* Scott, Seventeenth Report of the Fishery Board for Scotland, pt. iii. pp. 143-146. 

 t/6W.,PP. 153-156. 



J Scott, Fourteenth Report of the Fishery Board for Scotland, pt. iii. p. 167, 1895. 

 Scott, Thirteenth Report of the Fishery Board for Scotland, pt. iii. p. 247, 1894. 

 || See Ninth and Seventeenth Annual Reports of the Fishery Board for Scotland, part iii., 

 1890 and 1899. 



