BIOLOGY OF MAYFLIES OF THE GENUS BAETIS. 



EXPLANATION OF PLATE 



1. Diagram, genitalia 6 imago, B. pygmaea. 

 2 Diagram, genitalia 6 imago, B. postkatus. 



3. Diagram, life cycle, B. postkatus, May, 1919-May, 1920. 



Arrows indicate three successive broods. 



4. Venation, hind wing 6 imago, 5. pygmaea. 



5. Venation, hind wing 6 imago, B. propinquus. 



6. Venation, hind wing 6 imago, B. postkatus. 



7. Venation, fore wing 6 imago, B. postkatus. 



8. Diagram, 1st instar nymph, B. postkatus. 



9. Diagram, 1st and 2nd leg 6 imago, B. propinquus. 



10. Diagram, 1st and 2nd leg 6 imago, B. pygmaea. 



11. Diagram, 1st and 2nd leg 6 imago, B. postkatus. 



12. Diagram, genitalia 6 imago, B. propinquus. 



13. Diagram, labial palp nymph, B. pygmaea. 



14. Diagram, labial palp nymph, B. postkatus. 



15. Diagram, labial palp nymph, B. propinquus. 



16. Diagram, nematode in 6 imago, B. postkatus. 



17. Diagram, maxilla nymph, B. propinquus. 



18. Diagram, maxilla nymph, B. postkatus. 



19. Diagram, maxilla nymph, B. pygmaea. 



20. Diagram, mature nymph, B. postkatus. 



21. Diagram, egg mass, B. postkatus. 



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