MAY-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 Ephemeride, 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. 
