1901.] NATURAL SCIENX'ES OF PHILADELnilA. 141 



EXPLANATION OF PLATES II, III AND IV. 



All the figures are camera lucida drawings, and represent por- 

 tions of the gizzard linings, spread out flat. The fraction after 

 each name indicates how much of each lining is shown. A line 

 indicting a scale length of one- tenth millimeter is placed along- 

 side most of the figui'es. 



Plate II. 



Fig. 1. Calopteryx maculata. d^. ^. 



Fig. 2. Hetcerina americana. c? from Pennsylvania. ^. 



Fig. 3. Hetcerina americana. Larva. ^. 



Fig. 4. Protoneura sp. , group of sancta. ? . l , 



Fig. 5. Hetcerina vulnerata. ?. ^. 



Fig. 6. Vestalis luctuosa. d^. ^. 



Fig. 7. Vestalis apicalis. 9 . ^. . 



Fig. 8. Amphipteryx agrioides. cT. ^. 



Fig. 9. Lihellago caligata. d^. ^. 



Fig. 10. Euphcea impar. d. 5. 



Plate III. ; 



Fig. 11. Microstigma rotunclatuni. d'. 5-. 



Fig. 12. Enallagma ebrium. $. J^. The small fold f is not 

 developed in the portion figured. 



Fig. 13. Argia hipiuictulata. ^. 



Fig. 14. Megaloprepus cKvulatus. d. «-• 



Fig. 15. Xanthagrion erythroneurum. y\. Probably larval 

 gizzard; comj)are figs. 25-27. 



Fig. 16. Megapodagrion venale. d. ^. 



F'ig. 17. Ischnura verticalis. ^. 



Fig. 18. Heteragrion inca. d. ^. 



Fig. 19. Tatocnemis malagassica. ?. |-. 



Fig. 20. Paraphlehia sp. \. 



Fig. 21. Hemij)hlehia mirahilis. ?. ^. 



Fig. 22. Lestes vigilax. d. ^. 



Fig. 23. Mnais strigata. 9. ^. On either side of the right- 

 hand f fold is a row of 2-3 teeth, representing, prob- 

 ably, a series of still smaller folds. 



Fig. 24. Leptoenemis hilineata. d. ■^^ 



Plate IV. 



Fig. 25. Zichiiura verticalis. Larva, length 4 mm. {^. 

 Fig. 26. Ischnura verticalis. Larva, length 8 mm. ^. 

 Fig. 27. Ischnura verticalis. Larva, length 15 mm. 1. 



