of the Fishery Board for Scotland, 



171 







Dates. 







« 1 1 1 It-..*^ Ul l 1 IK >, 



1897. 





1898. 





Sept. 16. 



Dec. 12. 



March 31. 



July 6. 



COPEPODA. 













DtaptomiiS laeiniatus, Lilljeborg, 



f. 



0 





0 



fr. 



gracilis, G. 0. Sars, . 



f. 



0 





f. 



r. 



Cyclops strenuw, Fischer, . . 



f. 



f. 





fr. 



f. 



viridis (Jurine), , 



f. 



f. 





0 



0 



,, albkh.is (Jurine), 



0 



0 





fr. 



0 



Cladocera. 













Sida crystallina (MUller), 



f. 



0 





0 



0 



Holopedium gibberum, Zaddach, . 













Bosminu longispina, Leydig, 



0 



"o 





0 



fr. 



T)(_tplii) tv> Tiasuta, Gr. 0. Sars, . t 



fr. 



fr. 







c. 



Eurycerais lamellatus (MUller), . 



f. 



0 





r. 



0 



Camptocerevs rectirostris (Schcedler), 



f. 



0 





0 



0 



Bythotrephes longimmia, Leydig, , 



f. 



0 





0 



f. 



Leptodora hyalina, Lilljeborg, 



f. 



0 





0 



fr. 



Amongst the species named in this list the three following appear to 

 show distinct seasonal variation, viz. : — Diaptomus laeiniatus, Holo- 

 pedium gibberum, and Leptodora hyalina. Dapltnia nasuta also shows 

 a certain amount of variation, but it is less marked than that of these 

 three. Cyclops strenuus was more frequent in the gathering collected in 

 March than in the others ; while Dapltnia was much scarcer in this than 

 it was in the other gatherings. Sida, Eurycercus, and Camptocercus are 

 forms which I do not, as a rule, find in tow-net gatherings collected in 

 the open where the water is deep ; when these species do occur in tow-net 

 gatherings, the water they are collected in is usually shallow, and 

 aquatic vegetation is more or less in evidence. Holopedium occurred 

 only in the July gathering, in which it was moderately common, and 

 Diaptomus laeiniatus and Leptodora were frequent in the same gather- 

 ing. These last two forms were also present in the gathering collected 

 in September, but no trace of any of the three species was observed 

 in either of the other two gatherings collected. The Dapltnia, though 

 obtained in all the four gatherings, was much more plentiful in that 

 collected in July. It may also be noted that in the July gathering 

 collected with the fine tow-net infusoria and micro-algse were more or less 

 abundant. An organism somewhat resembling Nostoe was very plentiful. 

 It occurred in roundish masses of variable size, and in general appearance 

 was very like the objects observed a short time before in Loch Leven. 

 Actinophrys sol was also observed in the July gathering from Loch Doon, 

 as well as Ceratium, Diatoms, Desmids, &c. ; but a report on these may 

 be prepared later. 

 M 



