THE CANADIA.N ENTOMOLOGIST. 153 



first discoidal cell obliterated, rarely distinct, most fre- 

 quently confluent with the second discoidal 



cell Family XV., Oxybelidse. 



Head large, quadrate- or trapezoidal, the temples very broad; 

 scutellum normal, the i)ostscutellum unarmed without 

 squamte ; front wings with the first discoidal cell always dis- 

 tinct, separated from the second.. . Family XVI., Crabronidje. 



Abdomen with a strong constriction between the first and second seg- 

 ments ; eyes often emarginate within 4. 



Abdomen without a strong constriction between the first and second 

 segments ; eyes most frequently normal, rarely emarginate within. 



Abdomen sessile, never petiolate 3. 



Abdomen petiolate or subpetiolate ; cubitus in hind wings 

 usually originating before the transverse median nervure, 

 more rarely interstitial or originating slightly beyond it; 

 transverse median nervure not sinuate t^-shaped ; ocelli dis- 

 tinct ; labrum most frequently hidden, rarely triangularly 

 exserted, never free Family XVII., Pemphredonidse. 



Labrum large, free, well developed and triangularly elongated, much 

 longer than wide ; cubitus in hind wings usually originating be- 

 yond the transverse median nervure, the latter sinuate or some- 

 what (T'-shaped ; ocelli aborted, represented by 

 cicatrices Family XVIII., Bembicidise. 



Labrum small, not free, usually completely hidden by the clypeus ; 

 cubitus in hind wings most frequently originating beyond the trans- 

 verse median nervure, the latter straight, not •r'-shaped ; mandibles 

 often emarginate on under side ; ocelli distinct or at most with the 

 lateral or hind ocelli aborted or wanting, indicated by cicatrices ; 

 front wings with a distinct stigma Family XIX., Larridfe. 



Head wider than the thorax, the temples not narrow, rather broad ; 

 eyes most frequently normal ; rarely deeply emarginate within, 

 although often slightly emarginate within; abdomen most frequently 

 sessile or subsessile, rarely petiolate {Tac/iyptts, Klug), not elongate, 

 ovate or oblong-oval, and most frequently with a deep constriction 

 between the segments, or at least always with a constriction between 

 the first and second; front wings with three submarginal cells, the 

 second often petiolate, the second and third each receiving a 



