I4 ENTOMOLOGY 
Fic. 18 
ia} 
eh Ae) 
ad 
a at 
Aceh lT 7 
bh i nnty S 
Zo 
Staab bch 3a 
__ STP 
— 
A L 
Pteronarcys regalis. A, nymph (after NEwport); B, imago. Slightly reduced. 
Fic. 19. 
RB 
Hexagenia variabilis. A, nymph; B, imago. Natural size. 
