1 38 INSECTS. 



course, without wings), three beautifully-feathered tails, 

 much shorter than the tail-bristles of the perfect insect, 

 terminate the abdomen, and its sides are fringed with a 

 series of appendages which serve the double office of 

 gills and oars. The pupa3 may be known from the larvse 

 by the wing cases. 



In these early stages the Ephemera are predaceous, 

 feeding also, probably, on the decaying animal or vege- 

 table matter which abounds in their haunts at the 

 bottom of ponds and running streams. Some species 

 make burrows in the mud, where they remain on the 

 watch for prey passing by ; others are swift swimmers 

 and hunt in the open waters, having in the water, the 

 same faculty as that possessed by the Dragonflies in the 

 air, of altering their course without turning. 



The sub-imago has dull wings, fringed with fine hairs, 

 two or three tail-bristles, which are thinly covered with 

 hair, and which, with the legs, are shorter than those of 

 the perfect insect. 



The wings of the perfect insect, or imago, are 

 generally spotted and marked with brown, and have 

 a bright surface. In the male the tail bristles and 

 the fore-legs are larger than in the female, the 

 colours are brighter, and the eyes, which are larger, 

 are sometimes so divided as to form two pairs, of 

 which one pair is sometimes considerably elevated above 

 the other. There are three ocelli. Belated to the May- 

 fly is a small family, to which the Genus Perla belongs. 

 Most of these flies resemble the Ephemera in having 

 two tail-like bristles, but they differ greatly from them 

 in the proportion of their wings, the hind-wing in Perla 

 being generally much larger than the fore-wing,and folded 

 when at rest. Besides this the body is less elegant, being 



