* 
SCOTTISH FRESHWATER PLANKTON. 523 
The two Rotifers Notholca longispina, Kellicott, and Anurea 
cochlearis, Gosse, were very abundant in the plankton of Loch 
Tay ; and the following Rhizopods cecurred :—Arcella discoides, 
A. vulgaris var. gibbosa, Difflugia globulosa, Euglypha alveolata, 
and Trinema enchelys. 
In Loch Katrine the Rhizopods Cyphoderia Ampulla and 
Trinema enchelys were abundant. 
In Loch Achray Peridinium tabulatum was abundant, and 
Microgromia socialis, Diplophrys Archerii, and Arcella vulgaris 
were observed frequently. 
The Heliozoan Clathrulina elegans was plentiful in the plank- 
ton of all three lochs. Ceratiwm tetraceros was observed from 
Loch Katrine. 
Loch Doon, Ayrshire. 
Loch Doon is the largest loch in the South-west of Scotland, 
being some five or six miles in length. The head of the loch is 
situated near high mountains, which reach an altitude of 2668 ft. 
on the one side and 2764 ft. on the other. The material was 
collected in May 1902, chiefly towards the south end of the 
loch. 
The Rotifers Notholea longispina, Kellicott, and Anurea 
cochlearis, Gosse, were abundant; and Peridinium Wille, 
Huitfeldt-Kaas, and Mallomonas acaroides, Perty, were also 
frequent. 
The following Rhizopods were also observed in the plankton :— 
Centropyxis aculeata, Nabela collaris, N. flabellulum, and 
Euglypha ciliata. 
LINN, JOURN.—BOTANY, VOL. XYXY. 2k 
