Entomology of the Illinois River. 255 



KEY TO IM.AGOS OF ODONTOMYIA. 



Third vein from outer side of discal cell very imperfect 



or wanting, therefore not more than four posterior 



cells; small cross-vein distinctly present, though 



short. 



Basal two joints of antennae black, first twice as long 



as second. 



Front of $ piceo-ferruginous at middle, abdomen in 



both sexes with narrow lateral yellow marks at 



incisures intermedia. 



Front of $ black, abdomen of d^ with triangular 



lateral yellow spots jpubescens. 



Basal two joints of antennae ferruginous, about equal 

 in length. 

 Scutellum distinctly and rather densely punctate, it 

 and face black, or nearly so. 



Face in profile broadly rounded .plebeja. 



Face in profile strongly protuberant beneath an- 

 tennae pilimana. 



Scutellum smooth and shining, finely and very sparse- 

 ly punctulate, it and face light green, {extremis 



Day.) cincta. 



Third vein from outer side of discal cell fully developed 

 like those on either side of it, therefore five posterior 

 cells; small cro.^s-vein wanting and third and fourth 

 longitudinal confluent at that point, or the cross 

 vein extremely short. 

 Scutellum light greenish, with distinct spines. 

 Thorax with two spots; large species. 



Face of d* black hinotata. 



Face light greenish, with blackish fasciae in $. 



megacephala. 

 Thorax unspotted; a small species, face of male 

 piceo-testaceous, paler at middle, sides of male 

 abdomen broadly pale; spines small, distant 

 about half the length of the scutellum. ($ willis- 

 toni Day.) vertehrata. 



