THE FRESH-WATER LOCHS OF SCOTLAND, 
143 
pretty common in the loch. This is a larger species, usually dark blue 
in colour. It is a northern species, of general occurrence over the 
north and west of Scotland, but hardly known south of Loch Tay. 
Daphnia was always very scarce. Desmids of the genera Staurastrum 
and Arthrodes7iius were more numerous than is usual in great lakes. 
As in Loch Rannoch, skeletons of Glathrulina were abundant. 
Lochs luhhair and Bochart. — Both these lochs, being very shallow, 
had, at the time they were visited, in addition to the usual pelagic 
species of Diaptomus, Daphnia, and Bosmina, several species in 
abundance which are not truly pelagic. Chydorus sphccricus, Alonopis 
elongata, and Alonella nana were as numerous as the pelagic species. 
Rotifers and Protozoa, especially Rhizopods, were more varied than 
usual. 
Loch Essan. — Life was abundant and varied. Daphnia was of three 
forms — large typical Daphnia lacustris with rounded head, smaller 
with tall helmet (D . galeata), and an intermediate form. Diaptomus 
gracilis, some dark brown, some hyaline, Polyphemus, Biaphanosoma 
hrachyurum, Bosmina ohtusirostris, and water-mites (Hydrachnidse), 
which do not usually occur in the open water, were all common. 
Loch Breaclaich. — This loch was quite unusual from the great 
numbers of a Rotifer, AsplancLna priodonta, which formed a 
‘‘ Wasserblut,” appearing as a great slimy mass in the net. 
Diaptomus gracilis (hyaline). Cycloids (dark red), and Biaphanosoma 
hrachyurum were seen. 
T-jOch 7ia Lairige. — The characteristic organisms were Bosmina 
ohtusirostris (large dark brown, and purple) and a species of Conochilus. 
Daphnia galeata (with tall helmet), P olyarthra, and Diaptomus 
gracilis (pale, immature) were frequent. A few dark red Diaptomus 
gracilis, Sida crystallina, and Bythotrephes were also present. 
Loch Lyon. — The biology of this loch was notable for its unusual 
richness. Most abundant were Diaptomus gracilis (pale yellow), 
Bosmina ohtusirostris (with somewhat long spine), Cyclops strenuus (of 
large size), and Rotifers of many species. Larvae of Diaptomus were 
exceedingly numerous. 
Lochs Daimh and Giorra. — These two lochs are so nearly alike in 
size and so close together, being connected by a river, that they might 
be expected to resemble one another in their biology, but they were 
found to differ greatly. In Loch Daimh, Holopedium was abundant, 
but very young. Diaptomus gracilis (hyaline, with dark brown eggs) 
was numerous, and the larvae still more so. Nothing else was found in 
any numbers. Loch Giorra, on the other hand, had half a dozen 
common species — Diaptomus gracilis (pale yellow), Cyclops strenuus, 
Daphnia lacustris, Bosmina ohtusirostris, Dinohryon, and Tabellaria 
(two species). Holopedium was not seen. 
