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 phry- 

 ganece, which includes all those water flies 

 that have long antennas, 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 phryganeae (see 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 



