ii6 THE HABITS OF THE SALMON. 



summer, then the parasites must have lived in fresh 

 water about forty and sixty hours respectively. On 

 one occasion I caught a salmon with two unmis- 

 takable sea lice on it, in the month of June, about 

 half a mile below Abergeldie Castle on the Dee, in 

 Aberdeenshire. That must be quite sixty miles by 

 the river from the tideway at Aberdeen. Now the 

 streams of the Dee are, if anything, more rapid than 

 those of the Tay, and therefore it may be presumed 

 that this fish took a longer time to travel the distance ; 

 consequently the lice must have lived in fresh water 

 sixty hours, and in all probability longer. It is, 

 however, possible that in summer, sea lice live longer 

 in rivers when the water is warmer than at any other 

 time of the year. It could easily be ascertained how 

 long sea lice can live in fresh water in different 

 temperatures, by keeping fish in confinement in the 

 boxes at a weir just above the tideway in a river 

 into which fish run during spring, summer, and 

 autumn. The cages on the weir in the Galway 

 river would be very suitable for making such an 



