THE FRESH- WATER LOCHS OF SCOTLAND. 377 



loch, and is of the same order as those stories invented to explain why 

 the fox has a bushy tail and why the serpent crawls on his belly. 



NOTES ON THE BIOLOGY OF THE LOCHS IN THE LOCHY DISTRICT. 

 By JAMES MURRAY. 



There is little peculiarity in the biology of the large lakes in the 

 basin, except in that of Loch Lochy. They contain the ordinary fauna 

 of great lakes of low temperature. Most of them were surveyed so 

 early in the season that the water was little above the minimum winter 

 temperature, and the summer Crustacea (Holopedium, Leptodora, &c.) 

 had not arrived. The smaller lochs were warmer, and some of those 

 Crustacea were present. 



Loch Arkaicj. The plankton is almost exactly that typical of large 

 lakes, with hardly any local peculiarity. The larva of Leptodora, 

 which we have rarely found, was present. A few examples of the 

 somewhat rare Latona setifera were found. A few species of plankton- 

 desmids, chiefly of the genus Staurastrum, occurred, but they were less 

 conspicuous than in the lochs farther west. 



Loch Lochy. Though the situation of Loch Lochy is so similar to 

 that of Loch Ness, and though the depth in the two lochs is comparable, 

 the plankton of Loch Lochy offers a remarkable contrast to that of 

 Loch Ness. In two different years when the lochs were examined, the 

 plankton in Loch Lochy was found to be much richer. The quantity 

 was many times greater, the species more numerous, but the special 

 feature was the quantity and variety of the phytoplankton. Diatoms 

 were very abundant. Tabellaria fenestrata, var. aster ionelloides, was 

 of more luxuriant growth than had been observed elsewhere, the 

 colonies often making more than two complete turns of the spiral. 

 The rare crustacean Ophryoxus gracilis (discovered in Britain in Loch 

 Ness by Mr. D. J. Scour field) was present. The heliozoon Clathrulina, 

 of frequent occurrence in our larger lakes, but usually as skeletons 

 merely, was here abundant and alive, the majority of the examples 

 having the pseudopodia fully extended. 



Lochan na h-Earba. The fauna calls for little comment. Latona 

 setifera was found in the west loch. Of the summer Crustacea, Holo- 

 pedium was in both lochs, Leptodora only in the east loch, and 

 Diaphanosoma brachyurum only in the west loch. Desmids were 

 conspicuous in both lochs, and included some species which we have 

 not often found. 



Loch Lag y an. The plankton is quite ordinary, except that it is 

 the only loch of the basin where we observed two species of Diaptomus. 



