74 -THE WILLOW FLY 



two setae or whisks. Mr. Halford states that 

 he has never found it in the autopsies of trout 

 killed by him ; so presumably it is not accept- 

 able to chalk-stream trout. Possibly, however, 

 in other parts of the country, where insect 

 food is less abundant, it may be better appre- 

 ciated. The fact that a popular name has been 

 bestowed upon it points to anglers having found 

 the imitation of service. The yellow sally is 

 often confused with the yellow may dun, one 

 of the EPHEMERID^, quite different in appear- 

 ance, except in colour. 



Family . . PERLID^E 

 Genus . . Isopteryx 

 Species . . torrentium and tripunctata 



isopteryx Two small yellowish stone-flies, having the 

 appearance of diminutive yellow sallys, will be 

 known to most fishermen who frequent rocky 

 trout streams. These are Isopteryx torrentium 

 and Isopteryx tripunctata. The two species are 

 so nearly alike that it requires a practised eye 

 to tell the difference between them, and for 

 angling purposes, one artificial pattern may well 

 represent them both. 



Family . . PERLID.E 

 Genus . . Leuctra 

 Species . . geniculata 



PLATE XV 



Leuctra Leuctra geniculata, the Hampshire willow 



SwflV 3 .' ny, is so plentiful on the Test and Itchen in 



