292 THE FRESH-WATER LOCHS OF SCOTLAND 
1 Mollusc. — Pisid'mm pusillum (Gmel.). 
3 Crustacea. — Cyclops virklis, Jurine. 
Candona Candida (MiilL). 
Cypria oplithalmica^ Jurine. 
3 Worms. — StylodrUus Gabretecr, Vejd. 
Oligochaete, not determined. 
Automolos moi'giensis (Du Plessis). 
1 Insect. — Chironoinus (larva). 
Infusoria. — Several, ectoparasites on Plsid'uim and Cyclops^ not 
determined. 
Of casual occurrence at great depths are : — 
A brown species of Hydra ^ Loch Ness, 500-600 feet (J. Hewitt). 
Limncea peregra (Mi.ill.), Loch Ness, 400 feet. 
Proales dapknicola, Thompson, Loch Ness, 500 feet. 
Lynceus ctffivus^ Leydig, Loch Ness, 500 feet. 
At depths of from 250 to 300 feet about 40 species were found, 
excluding Rhizopods : — Crustacea, 14 species; Rotifera, 16 species; 
Gastrotricha, 2 species ; Tardigrada, 2 species ; Lifusoria, several 
species ; Insect larvae. Mites, Worms, etc. These records were obtained 
from one or two dredgings only, and the list could doubtless be 
greatly extended. 
Of Rhizopods, the most numerous group in the abyssal collections, 
practically all the species known in the lochs have been recorded for 
depths of 300 feet and more. These records are not satisfactorv, as 
many of them are founded on dead shells which may belong to species 
not capable of living at those depths. 
Supposed Peculiar Abyssal Forms. — Though I have made the 
general statement that no peculiar abyssal species have yet been 
found in the Scottish lochs, some of the workers at special groups 
have suggested that certain abyssal examples are more or less peculiar. 
Aidornolos inorgiensis (Du Plessis). — Mr Martin says that examples 
dredged at 500 feet in Loch Tay were without eyes. He does not 
suggest making a distinct variety or species on this account. In 
animals which have mere pigment spots as (so-called) eves, it is not 
difficult to understand how, after living for many generations beyond 
the influence of light, the eye-spots might disappear. Though they 
can hardly be regarded as organs of vision, they doubtless function 
in relation to light. It is otherwise with the more highly developed 
eyes of Cyclops viridis^ one of the most constant abyssal forms down 
to 750 feet. It appears to breed in the abyssal region — at least 
females carrying eggs are continually found. When brought to the 
surface from 700 feet these creatures, which mav be presumed never 
