246 SALMONIA. 



change into peculiar nymphae, that still re- 

 tain the power of swimming and moving, 

 from which the perfect insect is produced 

 during the summer heat. The flies, which 

 I mentioned to you in a former conver- 

 sation, under the name of the grannom, or 

 green tail, [see Jig. 2.) are of the class jphry- 

 ganecE^ which includes all those water flies 

 that have long antennae, and wings some- 

 thing like those of moths, but usually veined 

 and without powder. The yellow flies, 

 which you saw a short time since sporting 

 on the banks of the river, are of this kind. 

 The phryganeffi {^ee Jigs. 1, 2, 3, and 4.) 

 have four wings, which, when closed, lie flat 

 on their backs, the two upper ones being 

 folded over the lower ones : the flies called 

 by anglers the willow fly, the alder fly, 

 {see Jig. 4.) and the dun cut, are of this kind. 

 The phryganeae lay their eggs on the leaves 

 of willows, or other trees, that overhang the 

 water ; they are fastened by a sort of gluten 

 to the surface of the leaf: when hatched they 

 produce small hexapode larvae, which fall 

 into the water, and by a curious economy of 



