72 ILLINOIS BIOLOGICAL MONOGRAPHS [242 



EXPLANATION OF PLATE 

 Caudal Aspect of the Head 



Fig. y^)- Hypothetical head. 



Fig. 74. Tahanus giganteus, female. 



Fig. 75. Tabanus giganteus, male. 



Fig. 76. Bibiocephala elegantula, male. 



Fig. 77. SimuUum veiiustuin, female. 



Fig. 78. Trichocera biinacula. 



Fig. 79. Dixa clavata. 



Fig. 80. Rhyphus punctatus. 



Fig. 81. Sciara varians. 



Fig. 82. Psychoda albipennis. 



Fig. 83. Bibiocephala elegantula, female. 



Fig. 84. Promachus vcrtebratus. 



Fig. 85. Bittaconwrpha elavipes. 



Fig. 86. Rhabdopliaga strobiloides. 



Fig. 87. Mycetophila punctata. 



Fig. 88. Chironomus ferrugineovittatus. 



Fig. 89. Chironomus ferrugineovittatus, dorsal aspect. 



Fig. 90. Mycetobia divergens. 



