PIIRYGANEtf:. 211 



and 4,) have four wings, which when closed 

 lie flat on their hacks, 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, which over- 

 hang 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 nature collect round themselves, 

 some, parts of plants or small sticks ; some, 

 gravel; and some, even shell fish. They 

 spin themselves a sort of case of silk from 

 their bodies, and by a gluten, which exudes 

 from this case, cement their materials toge- 

 ther. They feed upon aquatic plants, and 

 sometimes upon insects, protruding only 

 their head and legs from the case. When 

 about to undergo transmutation, they quit 

 their cases, rise to the surface, and wait for 

 this process of nature in the air; but some 

 species fix themselves on plants or stones: 

 they burst the skin of the larvae, and appear 



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