144 BATHYMETRICAL SURVEY OF 



Loch Derculich. The characteristic animals were Diaptomus 

 (brown), Daphnia lacustris (with parrot-shaped head), Bosmina ob- 

 tusirostris (with long beak), Notholca longispina, and Dinobryon. 



Loch Scoly. The most abundant animals were Daphnia lacustris, 

 Diaptomus gracilis (dark brown, mostly immature), Conochilus volvox, 

 Bosmina obtusirostris (small), and Peridinium tabulatum. 



Loch Rannoch. The plankton of Loch Rannoch may be fairly 

 taken as" the type of all the large Scottish lochs. Almost every one of 

 the species included in the list of the lacustrine organisms was found in 

 it, and there was nothing in it not given in the list. Of the Entomos- 

 traca, Bosmina was the most abundant. Skeletons of the Rhizopod 

 Clathrulina elegans, though this is not a pelagic animal, were always 

 found in it. The biology of the littoral region of the loch has 

 been studied with some care by Mr. D. J. Scourfield and others, 

 but as this region has not been studied in the other lochs of the 

 system, it is thought better not to enter into the details of it 

 here. 



Loch Ba. Most of the common pelagic animals were not seen, while 

 many species belonging rather to the shore (or littoral) fauna were 

 numerous, as Eurycercus lamellatus, Acroperus harpce, Alonella nana 

 and A. excisa, Alona affinis and A. guttata, and Chydorus sphccricus. 

 Many Rhizopods were observed, as well as mites and Ostracodes. 



Loch Laidon. Only the Entomostraca of this loch were studied 

 by Mr. D. J. Scourfield. The species were all the same as in 

 Loch Rannoch. No collections were made of the other groups of 

 animals. 



Lochan Sron Smeur. Notwithstanding the high elevation and the 

 early season at which it was examined, this loch was found to be 

 exceptionally rich in both animals and plants, particularly in Rotifers, 

 Rhizopods, and Desmids. Holopedium was here seen unusually early 

 in the season. Besides the ordinary pelagic animals, Diaptomus, 

 Daphnia, Bosmina, &c., Latona setifera was present. 



Loch Bhac. The commonest animals were Diaptomus gracilis (red), 

 Bosmina obtusirostris (with long beak), Daphnia lacustris, Diaphano- 

 soma brachyurum. Among the Rotifers was the brilliant red and blue 

 Notops pygmceus, and the curious Desmid Micrasterias Wallichii was 

 present. 



Loch Con. Entomostraca were few, and Algae more numerous 

 than usual. The commonest animal was Bosmina obtusirostris (small). 

 Diaptomus gracilis (some large, yellow, others red). The Rotifer 

 Notops pygmceus was unusually large. 



Loch Tilt. In common with a few other lochs, usually lying at 

 considerable elevations, the only common animal was Diaptomus 

 gracilis, so bright red in colour that the net, when taken up, seemed 

 filled with blood. Hardly anything else was seen. 



