80 



ILLINOIS BIOLOGICAL MONOGRAPHS 



[250 



EXPLANATION OF PLATE 



Lateral Aspect of the Head showing the Tentorium 



Bibioccphala elegantula, female. 



Bibiocephala elegantula, male. 



Rhyphus punctatus. 



Trichocera bimacula. 



Psorophora ciliata, female. 



Stratiomyia apicula, male. 



Mycetobia divergens. 



Exoprosopa fasciata, eye removed. 



Dixa clavata. 



Empis clausa, female. 



Platypeza vclutina. 



Psychoda albipennis. 



Eristalis tenax, female, eye removed. 



Dolichopus bifractus, eye removed. 



Loxoccra pcct oralis. 



Rhabdophaga strobiloides. 



Sapromyza vulgaris. 



Drosophila ampelophila. 



Psilocephala haeinorrhoidalis, female. 



Aphiochaeta agarici. 



Euarcsta aequalis. 



Heteroneura flaviseta. 



Lonchoptera lutea. 



Tipula bicomis. 



Chyromya concolor. 



