328 THOMAS SAY FOUNDATION 



PLATE 19. 



Genitalia of Perla and Acroneuria. 



Fig. 1. Perla capitata Pict. $, dorsal view. 



Fig. 2. Perla capitata Pict. $ , side view. 



Fig. 3. Perla capitata Pict. $ , ventral view. 



Fig. 4. Perla media Walk. $ , dorsal view. 



Fig. 5. Perla media Walk. £ , ventral view. 



Fig. 6. Perla media Walk. eggs. 



Fig. 7. Perla immarginata Say 5, ventral view. 



Fig. 8. Perla immarginata Say $, dorsal view. 



Fig. 9. Perla immarginata Say eggs. 



Fig. 10. Perla immarginata $ genital hooks on tenth tergite. 



Fig. 11. Perla kansensis Bks. $ , dorsal view. 



Fig. 12. Perla Jcansensis Bks. $ , ventral view. 



Fig. 13. Acroneuria georgiana Bks. $ , ventral view. 



Fig. 14. Acroneuria georgiana Bks. $, dorsal view. 



Fig. 15. Acroneuria georgiana Bks. 9, ventral view. 



Fig. 16. Acroneuria georgiana Bks. $, variation in tip of subgenital 



plate. 



Fig. 17. Perla ramosa sp. nov. $ , ventral view. 



Fig. 18. Perla languida sp. nov. $, ventral view. 



Fig. 19. Perla languida sp. nov. $, dorsal view. 



Fig. 20. Perla languida sp. nov. $ , ventral view. 



