ILLINOIS BIOLOGICAL MONOGRAPHS 



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EXPLANATION OF PLATE 



Caudal Aspect of the Head 



Hypothetical head. 



Tabanus giganteus, female. 



Tnbanus giganteus, male. 



Bibiocephala clegantula, male. 



Simuiium venustum, female. 



Trichocera bimacula. 



Dixa clavata. 



Rhyphus functatus. 



Sciara varians. 



Psyclioda albipennis. 



Bibiocephala elegantula, female. 



Promachus vertebratus. 



Bittaconwrpha clavipes. 



Rhabdophaga strobiloides. 



Mycetophila punctata. 



ChiroHOmus ferrugineovittatus. 



Chirono)nus ferrugineovittatus, dorsal aspect. 



Mycetobia divergens. 



