12 OLD FLIES IN NSW DRESSES 



order to either kill them outright or at 

 any rate stop them struggling, and threw 

 them on the water. He was in such a 

 position that he could observe each fly 

 individually until it either floated past 

 or was taken by the fish. What he ob- 

 served was, that when in killing the fly 

 he had disturbed the natural position of 

 the wings, not one of the fish would look 

 at it ; while, if the wings remained in the 

 normal position of rest, the fly was always 

 taken. This occurred time after time, and 

 not once was the fly with the wings in an 

 unnatural position taken, but, on the other 

 hand, not a single fly with its wings in the 

 natural position of rest was allowed 'to 

 pass. He also observed that once or 

 twice the fish came up to look at a fly 

 whose wings had been disarranged, but 

 on getting close to it they always drew 

 back. 



This is, I think, an extremely strong 

 argument in favour of my theory. 



I do not propose in this work to deal 

 with Ephemeridae, as the wings in the 

 imitations now sold are in the natural 

 position. The families I do propose deal- 



