312 THOMAS SAY FOUNDATION 



PLATE 11. 



Wings of Isogenus, Perla and Clioperla. 



Fig. 1. Isogenus frontalis Newm. 



Fig. 2. Perla hastata Bks. 



Fig. 3. Perla postica Walk. 



Fig. 4. Perla crosoyi sp. nov. 



Fig. 5. Isogenus colubrinus Hag. 



Fig. 6. Clioperla gravitans sp. nov. 



Fig. 7. Perla expansa Bks. 



Fig. 8. Perla venosa sp. nov. 



