MA Y-FLIES. 61 



rendered the essential service of pointing out the 

 characters by which the sub-imago (pseudimago) can 

 be distinguished from the imago ; they consist in the 

 dull membrane of the wings, the presence of deli- 

 cate fringes of hairs on the margin of the wings, and 

 the distinct hair of the caudal filaments. The form 

 of the sub-imago is analogous to that of the imago, 

 but the caudal filaments and legs are shorter. The 

 colouring often differs essentially ; that of the body 

 is generally paler, with greyish tinge; that of the 

 opaque wings is always darker, yellow, grey, or even 

 blackish, but not bright." The structural differences 

 referred to are shown in the illustration. To put the 

 subject in its simplest and clearest form, it may be 

 tabulated thus : 



ENTOMOLOGIST. FISHERMAN. 



Ephemera vulgata (pseudimago) (1) . The Green Drake (3). 

 Ephemera vulgata (imago) (2) . . The Grey Drake. 



The May-fly belongs to the class of insects known 

 to entomologists as the Ephemeridse, the name derived 

 from a Greek word signifying diurnal their short 

 span of life, as perfect insects, seldom exceeding the 

 space of a few hours. Many readers must recollect 

 Dr. Franklin's beautiful address, alleged to have been 

 delivered by an aged ephemera, that had lived four 

 hundred and twenty minutes, as one of the most pro- 

 foundly humiliating lessons ever read to proud human 

 nature. 



