8 EPHEMERIDyE OF THE ClIALK STREAMS. 



been fertilised by coition the females of some species flutter 

 above the surface of the stream ,. dipping at intervals to wash off 

 batches of eggs which collect towards the lower extremity of 

 the abdomen. In some cases the eggs are discharged en bloc. 

 These eggs sink to the bottom, and in due course go through 

 the various stages which have just been described. After the 

 eggs have all been expelled the female quickly dies from exhaus- 

 tion. Falling prone upon the surface of the stream, she floats 

 down with wings outstretched to find her last resting place in 

 the belly of a hungry trout or who shall say where ? 



The males have no inducement to take them to the water 

 to meet their end, and when a spent male is found on the 

 surface he is only there because he happened to be flying over 

 the water at the moment his strength gave out. This is the 

 reason why males are met wdth so much less frequently than 

 females, and it is well for an angler who has picked up a spent 

 male to be sure that he has not chanced upon an odd one, while 

 the fish are really feeding on the much more numerous females. 



To anyone who has followed what has gone before it will 

 at once become abundantly clear that the difficulty has now 

 been further complicated by the introduction of two sexes and 

 two conditions, making each separate species equal to four as 

 far as identification is concerned. The average fisherman is 

 apt to- refer casually to an artificial fly as, say, an Olive, but 

 this somewhat sloppy process fails to work when applied to 

 the natural insect. In the case of a living Olive the fly will 

 come under one of the following heads : 



(1) A male Olive Dun. 



(2) A female Olive Dun. 



(3) A male Olive Spinner. 



(4) A female Olive Spinner. 



And it cannot be adequately described at any less length. 



It now becomes necessary to get rid of these complications 

 which have newly arisen, and it is fortunate that neither 



