EIGHTH DAY.] PHR YGA NEJE. 211 



water flies that have long antennae, and wings 

 something like those of the 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 phryganese (see fgs. 

 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 fig. 4,) and the dun 

 cut^ are of this kind. The phryganese 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 larvse, 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, that exudes from this case, cement 

 their materials together. 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 larvse, and appear 

 perfect animals, male and female, fitted for the office 



