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, Diaptumus, Daphnia, and Bosmina being taken in all the 
gatherings. Holopedium, though common in September and June, was 
not observed in November and March; Bythotrephes 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 \SiJ on gill a 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. J 
Twenty-five species of Crustacea and four species of Mollusca are 
recorded from Loch Lubnaig, including a new cladoceran {Mona 
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 Sphceriuni corneuni, Pisidium fontinale, 
Valvata g)iscincdis, and Planorhis contortus. 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. Daplinice, were 
* Scott, Seventeenth Report of the Fishery Board for Scotland^ pt. iii. pp. 143-146. 
j* Ibid.^ pp, 153-156. • . 
t 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. 
II See Ninth and Seventeenth Annual Reports op the Fishery Board Jor Scotland, part iii., 
1890 and 1899. 
