150 PROC. ENT. SOC. WASH., VOL. 21, NO. 6, JUNE, 1919 



Fig. ii. Genitalia of Zachizonyx montana (Cress.), abossicular surface (sec- 

 ondarily), ventral? 



Fig. 12. Gentialia of Philomastix naucarrowi (Froggatt), abossicular sur- 

 face (secondarily), ventral? 



Fig. 13. Genitalia of Pterygophorus cinctus (Klug), abossicular surface 

 secondarily), ventral? 



Fig. 14. Genitalia of Cimbex americana, var. luctifera (Klug), ossicular 

 surface (secondarily), dorsal. 



Fig. i5. 2 Genitalia of Polyselandria flavipes (Nort.), ossicular surface (sec- 

 ondarily), dorsal. 



Fig. 16. Genitalia of Pteronidea ventralis (Say), ossicular surface (second- 

 arily), dorsal? 



Fig. 17. Genitalia of Tenthredella verticalis (Say), ossicular surface (sec- 

 ondarily) dorsal. 



Fig. 18. Genitalia of Hemitaxonus dubitatus (Nort.), ossicular surface (sec- 

 ondarily) dorsal. 



Fig. 19. Genitalia of Cephaleia fascipennis (Cress.), ossicular surface 

 (primitively) ventral. 



Fig. 20. Genitalia of Xiphydria mellipes (Say), ossicular surface (primi- 

 tively) ventral. 



Fig. 21. Genitilia of Cephus cinctus (Nort.), ossicular surface (primitively) 

 ventral. 



Fig. 22. Genitalia of Perga dorsalis (Leach), ossicular surface (secondarily) 

 dorsal. 



Fig 23. Genitalia of Eriocampoides amygdalina, Rohwer (paratype) ossicu- 

 lar surface (secondarily), dorsal? 



Fig. 24. Genitalia of Zachizonyx montana (Cress.), ossicular surface, (sec- 

 darily) dorsal? 



Fig. 25. Genitalia of Philomastix naucarrowi (Froggatt), ossicular surface, 

 (secondarily) dorsal? 



Fig. 26. Genitalia of Pterygophorus cinctus (Klug), ossicular surface, (sec- 

 darily) dorsal? 



Fig. 27. Genitalia of Megaxyela aenea (Nort.), abossicular surface, (primi- 

 tively) dorsal. 



Fig. 28. Genitalia of Megaxyela aenea (Nort.), ossicular surface, (primi- 

 tively) ventral. 



Fig. 29. Styli and genitalia of ephemerid Blastunis cupidus, male, ventral 

 view. 



Fig. 30. Parameres and penis of apterygotan (Machilis polypoda, male, 

 ventral view (after Crampton, igiSa). 



Fig. 31. Terminal segments and gonopods of Mecopteron Xannochorista 

 dipteroides, male, dorsal view (from Crampton, 191 8b, after 

 Tillyard). 



- The upper right hand label "pa" in Fig. 15 should read "pal." 



