194 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxiii. 



3. Labrum large, free, well developed, and triangularly elongated, much longer than 



wide; cubitus in hind wings usually originating beyond the trans- 

 verse median nervure, the latter sinuate or somewhat <r' -shaped; 

 ocelli aborted, represented by cicatrices. 



Family XVIIl. BEMBicin.'E. 

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

 wings most frequently originating beyond the transverse median 

 nervure, the latter straight, not cp -shaped; mandibles often emargi- 

 nate 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. Larrid.e. 



4. 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 sub- 

 sessile, rarely petiolate {Tachypus 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 cubital cells, the second 

 often petiolate, the second and third each receiving a recurrent 

 nervure; cubitus in hind wings variable, inerstitial or nearly, origi- 

 nating far beyond the transverse median nervure. 



Family XX. Philanthid.e. 

 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 one or two 

 cubital cells, the second, however, usually more or less indistinct or 

 subobsolete; cubitus in hind wings originating beyond the trans- 

 verse median nervure Family XXI. Trypoxylid^. 



5. Abdomen without a constriction between the first and second segments; interme- 



diate coxfe not contiguous 6 



Abdomen with a more or less distinct constriction between the first and second 

 segments, the first segment coarctate; intermediate coxpe contiguous; 

 mesosternal suture wanting Family XXII. I\Iellinid.e. 



6. Mesosternum produced into a forked process posteriorly; mesepisternum not 



separated; mesonotum with distinct parapsidal furrows 8 



Mesosternum normal, not produced into a forked process posteriorly; mesepis- 

 ternum 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 transver.se 

 median nervure, rarely slightly beyond it, the latter most frequently 

 straight, rarely sinuate or somewhat c-' -shaped. 



Family XXIII. Nyssonid.e. 

 Labrum free, well developed, subtrianguar or semicircular, wider than 

 long; cubitus in hind wings originating usually before the trans- 

 verse median nervure, the latter strongly sinuate or somewhat 

 (f'-shaped; ocelli distinct Family XXIV. Stizid.e. 



7. Clypeus never produced posteriorly between the antennfe, the latter inserted 



above the base of the clypeus; metathorax most frequently rounded 



"posteriorly, very rarely with acute angles; cubitus in hind wings 



variable, most frequently originating heijond the transverse median 



nervure, more rarely interstitial Family XXV. Sputxin^E. 



