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EPHEMERA. EPHEMERA. 
Generic Character. 
Os edentulum, absque pal- 
pis. 
Stemmata duo, maxima, 
supra oculos. 
Alee quatiior, erectae; pos- 
ticis rninoribus. 
Cauda setosa. 
Mouth without teeth or 
feelers. 
Stemmata two, very large, 
above the eyes. 
Wings upright; the lower 
pair smaller. 
Tail bristled. 
TThIS genus, like that of Libellula, exhibits a 
wonderful difference between the same animal in 
its larva state and that of its ultimate or perfect 
state ; the larva being altogether aquatic, the 
complete insect aerial. It also afibrds an example 
of what may be termed a flying pupa ; since, 
in some species at least, the insect is no sooner 
evolved from the larva than it flutters to the near- 
est convenient spot, and again shifts its pellicle*, 
the wings themselves having cast their exterior 
membrane. The Ephemeras are extremely short- 
lived insects. The most familiar species is the 
Ephemera vidgata or common May-Fly, so plenti- 
ful in the early part of summer about the brinks 
* This operation is so quick that it may be rather called 
springing from the chr\'salis than gradually emerging. 
