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Family SPHEGIGASTRIDES. 

 I pper wings with a delicate marginal vein, petiole punctale above, longer than 

 broad. 

 Petiole longer than the posterior coxae; $ palpi normal. 

 Head with compressed cheeks; vertex not very narrow. 



Parapsides discernible *Genus Merismus Walker. 



l'arapsides not plainly discernible. 

 Abdominal joints 2 and 3 very large ..*Genus Sphegigaster Spinola. 



Abdominal joint 2 very large, others short, often retracted 



*Genus Cryptoprymnus Foerster. 

 Head with rounded cheeks, sub-lenticular, vertex narrow ; postpetiole very large: 



collar broad *Genus Syntomopus Walker. 



Petiole not longer than posterior coxa?; second segment of abdomen deeply emargi- 

 nate and third very large; $ palpi abnormal. 



Vertex acute in the middle; parapsides not plainly discernible 



*Genus Cyrtogaster Walker. 



Vertex not acute medially; parapsides plainly discernible 



*Genus Polycystus Westwood. 

 Upper wings with a thick marginal vein; petiole shorter than the posterior coxa;. 



Parapsides plainly separated; stigmal club large *Genus Pachycrepis Foerster. 



Parapsides not plainly distinguished Genus Pachyneuron Walker. 



Tribe DIPARIDES. 



l'etiole shorter than posterior coxae; $ antennae not verticillate-pilose 



*Genus Panstenon Walker, 

 l'etiole linear, longer than coxae; postpetiole very large; $ antennae with well separ- 

 ated joints, sparsely verticillate *Genus Dipara Walker. 



Tribe PTEROMALIDES. 



Posterior tibiae 2-spurred *Genus Dimachus. 



Posterior tibiae 1 -spurred. 

 Antenna] club subulate Q, or conico-acuminate $; metathorax punctate, no fold 



and no spiracular sulcus .... Genus Merisus Walker. 



\11tennal club not subulate. 

 Antennas inserted below the middle of the face; stigmal club scarcely discernible; 

 vertex not medially acute; cheeks round; abdomen not rotund; left mandible 

 3-, right 4-dentate; joint 1 ot the antennal funicle equal to the others in size, 



rarely abruptly smaller Genus Eutelus Walker. 



Terebra exserted; funicle of antennae thick, joint 1 in the O abruptly smaller; 



thorax above smooth; metathorax very short 



Genus Roptrocerus Ratzeburg. 



Joint 1 of the antennal funicle most usually large, very rarely abruptly smaller 



than the others; posterior coxa? not pubescent on the hind margin at base; 



left mandible usually 3-dentate, dentations broad at base 



*Genus Aetroxys Westwood . 

 Vnterior margin of the collar sharp, acutely reflected; mandibles acutely 4- 



dentate *Genus Isocyrtus Walker. 



I lead with the vertex sometimes medially acute; eyes occasionally hairy; mandi- 

 bles usually 4-dentate; antennae often inserted below the middle of the face; 

 liny; joint plainly discernible; metathorax usually punctulate and furnished 



