SPHEGID^. 181 



6*. Median segment not particularly long, 

 not flat above nor cariiiated. 

 a'. Labrum very much lengthened 

 and exserted beneath clypeus. 

 a^. Labrum sharply acute at apex, 



rostriform Bbmbex, p. 284. 



6*. Labrum rounded at ajjex, not 



rostriform Stizus, p. 276, 



i'. Labrum short, not or very in- 

 conspicuously exserted beneath 

 clypeus. 

 a®. The 2nd cubital cell receiving 

 both recurrent nervui-es. 

 a'. The 2nd cubital cell petiolate ; 

 median segment with lateral 



tubercles or spines Nysson, p. 2G8. 



b~. The 2ud cubital cell not petio- 

 late ; median segment without 

 lateral tubercles or spines . . Gorytes, p. 271. 

 b^. The 1st cubital cell receiving the 



1st, the 2nd cubital cell the 2nd [p. 270. 



recurrent nervure Heliory'Ctes, 



c^. The 2nd cubital cell receiving 

 the 1st, the 3rd cubital cell the 

 2nd recurrent nervure. 

 a'. 2nd cubital cell petiolate .... Cerceris, p. 299. 

 b''. 2nd cubital cell not petio- 

 late Philanthus, 



b. Abdomen petiolate, petiole composed of ven- [p. 293. 



tral plate only of basal abdominal seg- 

 ment. 

 a'. Intermediate tibife with two apical spurs. 

 a^. Second and third cubital cells in fore wing 



each receiving a recurrent nervure .... Sphex, p. 241. 

 h'^. Second cubital cell in fore wing receiving 



both recurrent nervures. [p. 228. 



«^. Anterior tarsi ciliated exteriorly Ammophila, 



¥. Anterior tarsi not ciliated exteriorly . . Sceliphbon, 

 6'. Intermediate tibia; with one apical spur. [p. 23o. 



a^. Three cubital cells in fore wing Psen, p. 262. 



b'\ Two cubital cells in fore wing. 



a?. With one recurrent nervure in fore 



wing Stiqmus, p. 266. 



l^. With two recurrent nervures in fore 

 wing. 

 a*. Petiole long, longer than succeed- [p. 265. 



ing abdominal segment Pemphredon, 



6*. Petiole short, shorter than succeed- 

 ing abdominal segment Passalcecits, 



[p 267. 



