Plate LIX 

 Nymphal Structures 



Fig. 14. Lestes rectangularis, wing-case. 



Fig. 15. Hetaerina americana, wing-ease. 



Fig. 16. Enallagma signatum, wing-case. 



Fig. 17. The same, young nymph, wing-ease. 



Fig. 18. Ischnura verticalis, caudal end of the abdomen 

 with the two lateral gills removed. 



Fig. 19. Enallagma exsulans, tarsus. 



Fig. 20. The same, leg. 



Fig. 21. Ischnura verticalis, dorsum of meso- and 

 metathorax. 



Fig. 22. Agrion muculatum, maxilla. 



Fig. 23. Hetaerina americana, dorsum of the prothorax. 



Fig. 24. Ischnura verticalis, ventral aspect of thorax 

 and cephalic segments of abdomen. 



Fig. 25. The same, lateral aspect of thorax and ab- 

 domen. 



Fig. 26. Enallagma sp., cross-section of gills. 



