of the Fishery Board for Scotland. 



153 



notwithstanding all this, its temperature for September, November, and 

 March is really lower ; but, on the other hand, when the loch was visited 

 on the 28th of June, when the weather was, and had been for some time, 

 warm and dry, and the stream flowing into it from Loch Katrine had 

 consequently become much reduced, so that there was less movement in the 

 water to equalise the temperature, the surface temperature was found to be 

 considerably higher than that of any of the lochs previously examined. 

 The surface and bottom temperature of Loch Achray exhibited in Septem- 

 ber a difference of only 2 degrees Fahrenheit, whereas the difference 

 between surface and bottom temperature in June was over 15 degrees. 

 In November and March the water appeared to be of a nearly uniform 

 temperature. The difference between the highest and lowest surface 

 readings is fully 23 degrees, but there is only a difference of 9 degrees 

 between the highest and lowest readings at ten fathoms. 



Pelagic Entomostraca captured by Tow -Net. 



In the following list of Entomostraca captured with the tow-nets, it will 

 be observed that Holopedium, though common in the gatherings collected 

 in September and June, is not represented in those collected in September 

 and March — which confirms what is said under Loch Arklet as to the 

 influence on this species of seasonal changes — so far, at least, as regards its 

 appearance in the smaller lochs. Bythotrephes also appears to be subject 

 to somewhat similar seasonal variation. Daphnia, on the other hand, is 

 apparently not so much affected by mere seasonal change. In Loch 

 Achray, as in other lochs, Daphnia is one of the very few pelagic forms 

 found in all the four gatherings that were collected. 



Table containing the Names of the Entomostraca Collected in 



the Tow-Nets. 





Dates. 



Names of the Species. 



1897. 



1898. 





Sept. 10. 



Nov. 27. 



March 17. 



June 28. 



COPEPODA. 











Diaptomus gracilis, G. 0. Sars, - 

 Cyclops strenuus, Fischer, 

 leuckarti, Claus, 



r.(fr. infine 

 net), 

 f. 



0 



r.(fr. infine 



net), 

 r. (fr. infine 



net). 

 0 



f. 

 0 



0 



r.(fr. infine 

 net), 

 f. 



f. 



viridis (Jurine), 



r. 



f. 



0 



0 



albidus (Jurine), 



r. 



fr. 



0 



0 



Cladocera. 











Holopedium gibberum, Zaddach, - 



c. 



0 



0 



c. 



Daphnia galeata, G. 0. Sars, 



c. 



fr. 



f. 



c. 



Bosmhia longispina, Leydig, 



f. 



f. 



f. 



f. 



Eurycercus lamellatus (Midler), 



0 



fr. 



0 



0 



Ahmopsis elongatus, G. 0. Sars, - 



0 



0 



0 



r. 



Bythotrephes longimanus, Leydig, 



f. 



0 



0 



f. 



Leptodora hyalina, Lilljeborg, 



f. 



0 



0 



0 



