378 
BATHYMETRICAL SURVEY OF 
One was the common D. gracilis, the other difficult to determine, owing 
to the lack of fully matured examples, but almost certainly D. laticeps. 
Loch Ossian and Loch Ghuilhi7in. — The fauna of these lochs is in no 
way peculiar. Desmids were scarce in Loch Ossian, and abundant in 
Loch Ghuilbinn, where, among others, Staurastrum o'phiura occurred. 
Loch Treig. — Bosmina ohtusirostris had a very long spine, approach- 
ing the variety longispina, as found in Loch Morar. This is the only 
large lake where we found the rotifer Triarthra longiseta. Skeletons 
of Clathrulina were abundant. The phytoplankton was fairly rich in 
species, and about a dozen Desmids were noted. 
An Duhh Lochan. — This was examined very late in the season. 
The chief peculiarity noted was the red colour of the Biaptomiis, a 
feature found in more marked degree in Lochan Lunn da-Bhra. 
Desmids were abundant, and the two fine species, Staurastrum 
hraziliense and S. longispinum, occurred. 
Lochan Lunn da-Bhra. — The Diaptonius in this loch was so deep 
red that, when the nets were taken out after towing, they seemed to 
contain blood. 
Loch nan Gahhar. — From its shallow, weedy character, an abundant 
fauna would be expected here, yet we found the collections exceptionally 
poor. 
