THE FRESH- WATER LOCHS OF SCOTLAND. 291 
character. Any slight peculiarity in the fauna will be noted under the 
name of each loch. 
In contradistinction to the absence of western species in the fauna of 
these lochs, is the occurrence in the flora of several Desmids of the 
western type. These western Desmids, though less numerous than in 
districts both to the north and south, are in most of the lochs. 
Loch Gown, North and South . — These very shallow basins had an 
admixture of littoral species in the plankton, and the numerous 
Desmids included both pelagic and bog species. 
Loch o' Chroisg . — The only peculiarities of this loch were the 
abundance of algse and of the smaller pelagic animals, such as Rotifera 
and Protozoa. Floscularia pdagica, Rousselet, was abun<dant. 
Loch Achanalt. — Owing to its shallow weedy character, littoral 
species were more numerous than pelagic ones. A species of Gammarus 
was of a bright slaty blue colour. Ophridium was abundant on the 
weeds. 
Loch a’ Chuildin . — Among the Rotifera observed were Euchlanis 
lyra, E. dilatata, and Plocsoma truncatum. The Desmid Staurastrum 
arctiscon was frequent. 
Loch Fa7inich. — As in most of our largest lakes, there were skeletons 
of Glathrulina elegans floating in the water. Although this is not a 
true plankton organism (it lives attached by a stalk to plants), the 
skeletons have seldom or never been observed during the Lake Survey 
work except in large lakes, while it has rarely been seen living at the 
margins of those lakes. The lightness of the skeletons, enabling them 
to float on fresh water, may serve for the distribution of the species, and 
small cysts are commonly seen in them. Granting this, their absence 
from smaller lakes is still unexplained. The only suggestion I can offer 
is that the lower specific gravity, resulting from the higher temperature 
of smaller lakes, may prevent the floating of the skeletons, or that the 
higher temperature may lead to a more rapid decomposition of the 
material of which they are composed, and so prevent their accumulation 
in the water. 
Loch Garvc. — There was nothing peculiar in the plankton, except 
the apparent absence of Desmids. 
Loch Luichart. — In contrast with the neighbouring Loch Garve, 
Desmids were here abundant, and other algse were also numerous. 
Loch Achilty. — Desmids were numerous, including, among species 
of the western type, Staurastrum arctiscon and S. jaculiferum . 
Loch KiiieUan. — Ceratium hirundinella was very abundant, of a 
form with long divergent middle horns. There were also observed 
V olvox glohator, Asterionella with very short rays, a species of Cerio- 
daphnia, and a few larvse of Gorethra. 
Loch Ussie. — Ceratium hirirndmella, of the same form as in Loch 
Kinellan, was the most abundant organism. This was the only loch in 
the district in which Latona setifera was seen. 
