EVOLUTION OF THE TROUT FLY. 151 



The Blue or Olive Dun is, I believe, the second 

 Dun fly of the Treatise : 'the body of black wool, 

 the wings of the blackest drake, and the jay 

 under the wing and under the tail.' That 

 dressing is not easy to construe, and I suspect 

 the text is corrupt. It is plain that the fly had 

 a black wool body and I think wings from the 

 quill feather of a drake : not the dark mottled 

 feather, usually called dark mallard; for I 

 think (though it is only a matter of opinion) 

 that when the mottled feather, light or dark, 

 is intended, the Treatise uses the word 'mail/ 

 which would be an appropriate word for a body 

 feather. So our fly has a black wool body and 

 clear dark wings of a drake's wing feather : 

 but what is the meaning of jay under the wing 

 and under the tail ? Does it mean a jay hackle 

 run all down the body from wings to tail, and is 

 this hackle the blue feather, or what is it? It 

 is difficult to say. Markham, who corrected so 

 many of the ambiguities of the Treatise, saw 

 this difficulty, for he gives a dressing materially 

 different : body of black wool and wings of the 

 dun feathers of a drake's tail. That is plain 

 enough, and both dressings are fairly good, 

 though a little dark even for the Dark Olive. 

 Cotton gives two Blue Duns, one for February 

 and one for March, besides a Great Dun for 

 February, the best fly for the month, giving 

 admirable sport. He is therefore confusing, 

 but as all three are so alike as to be practically 

 indistinguishable, I take the dressing of the 



