EXPLANATION OF PLATE XIX. 



Fig. I. — Wings of Perla henigna, Ndm. 



,, 2. — End of male abdomen of same, dorsal view. 



,, 3. — The same in lateral view. 



„ 4. — Base of seta and recurved appendage of its base, as viewed 

 from within. 



,j 5. — End of male abdomen of Perla ione, Ndm., in lateral view. 



,, 6, 7. — Outlines of eggs of same. 



^, 8. — The ventral aspect of the eighth and ninth segments of 

 the female of the same species. 



,, 9. — Like view of the same parts in Perla cymhele, Ndm. 



,, 10. — The egg of Perla cymhele, Ndm, 



,, II. — Wings of Perla duvaucelii, Pict., male. 



„ 12 — 14. — Dorsal, ventral and lateral views, respectively, of the 

 tip of the abdomen of the male in the same species. 



,, 15. — Wings of Cryptoperla torva, Ndm. 



,, 16. — Foot of same. 



,, 17. — Base of antenna of same. 



,, 18. — Base of abdominal seta of same. 



,, 19. — Lateral view of the seventh, eighth and ninth abdominal 

 segments of the female of the same species, showing 

 enormous lamina. 



,, 20. — Maxilla of the same. 



,, 21. — Labium of the same, showing reduced palpi. 



