64 ILLINOIS BIOLOGICAL MONOGRAPHS [234 



EXPLANATION OF PLATE 

 Cephalic Aspect of the Head and Mouth-parts 



Hypothetical head. 

 Siinuliuin vcnnstiiin , female. 

 Siuniliuni johannseni, male. 

 Bibiocephala clcgaiitiila, male. 

 Bibiocephala elegantula, female. 

 Rhabdophaga strobiloides. 

 Mycctobia divcrgcns. 

 Psychoda albipennis. 

 Rhyphns punctatns. 

 Psorophora ciliata, female. 

 Mycetophila punctata, female. 

 Chiro)ioi)!us ferrugincovittatus, female. 

 Bibio fcinoratus, male. 

 Bibio femoratus, female. 

 Ptychoptcra rufocincta. 

 Trichocera bimacula. 

 Sciara varians. 

 Tiptila bicornis. 



