154 THE CANADIAN ENTOMOLOGIST. 



recurrent nervure ; cubitus in hind wings variable, interstitial 

 or nearly, or originating far beyond the transverse median 



nervure Family XX., Philanthidte. 



Head not wider than the thorax, the temples very narrow or flat ; eyes 

 always deeply emarginate within, or reniform ; abdomen elongate, 

 clavate, the first segment elongate, petioliform ; front wings with 

 two submarginal cells, the second, however, usually more or less 

 indistinct or subobsolete ; cubitus in hind wings originating beyond 

 the transverse median nervure Family XXL, Trypoxylidse. 



5. Abdomen without a constriction between the first and second seg- 



ments ; intermediate coxae not contiguous 6. 



Abdomen with a more or less distinct constriction between the first 

 and second segments, the first segment coarctate ; intermediate 

 coxae contiguous ; mesosternal suture 

 wanting Family XXII., Mellinidc^. 



6. Mesosternum produced into a forked process posteriorly ; mese- 



pisternum not separated ; mesonotum with distinct parapsidal 



furrows 8. 



Mesosternum normal, not produced into a forked process posteriorly ; 

 mesepisternum separated ; mesonotum without parapsidal furrows, 

 or at most only vaguely defined. 



Abdomen distinctly petiolated 7. 



Abdomen sessile or subsessile. 



Labrum not free, entirely covered by the clypeus, or 

 at most with only its apex visible ; cubitus in hind 

 wings originating before the transverse median nervure, 

 rarely slightly beyond it, the latter most frequently 

 straight, rarely sinuate or somewhat 

 c^-shaped ... Family XXIII., Nyssonidre. 



Labrum free, well developed, subtriangular or semicir- 

 cular, wider than long ; cubitus in hind wings originating 

 usually before the transverse median nervure, the latter 

 strongly sinuate or somewhat c^-shaped ; ocelli 

 distinct Family XXIV., Stizidas. 



7. Clypeus never produced posteriorly between the antennae, the latter 



inserted above the base of tiie clypeus ; metathorax most frequently 

 rounded posteriorly, very rarely with acute angles ; cubitus in hind 



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