NORTH AMERICAN HYMENOPTERA. 173 



.Subfamily PLATYGASTERINiE. 



Siihmarginal vein with a knob at tip. 



Tarsi 4-jointed Genus IphetraclielH!^ Haliday. 



Tarsi 5-jointed. 



Antennffi 9-jointed, dentate with % Genus Allotropa Foerster. 



Antenna? 10-jointed. not dentate with % . 

 Wings with a basal and a median vein. 



The three hist funicle joints much larger than the rest, forming a club. 



Genus Metaclisis Foer-ster. 

 The last joint alone longer than the preceding. 



Genus IVloiiocrita Foerster. 

 Wings without basal and median veins. 



The basal ocelli nearer the apical than to the inner border of the eye. 



Genus li^ostasius Foerster. 

 The ba-sal t>celli nearer the inner border of the eye than to the apical 

 ocellus. 

 The 9 with a horn on first abdominal segment. 



» Genus Inosteniina Haliday. 



The 9 without such a horn Genus Aeerota Foerster. 



Submai'ginal vein without a knob at tip. 



Scutellum more or less lengthened, never semi-circular, or when shortened it 

 is compressed at the sides and furnished with an aw'1-shaped or 

 warty tip. 



Thorax strongly compressed from sides Genus CatillliS Foerster. 



Thorax not compressed. 



Scutellum lengthened, without thorn-, awl-, or wart-shaped tip. 

 Parajisidal furrows deep, parallel behind. 



Genus Xestoiiotus Foerster. 

 Parapsidal furrows very faint or absent. 



Genus Ainblyaspis Foerster. 

 Scutellum lengthened, with a thorn-, awl-, or wart-shaped tip. 

 Scutellum extended in a more or less strong thorn. 



Basal ocelli nearer the eyes than to the apical ocellus ; club of 9 



4-jointed f Genus Leptacis Foerster. 



Basal ocelli not nearer the eyes; club of 9 3-jointed. 



Genus Isorlioinbus Foerster. 

 Scutellum extended in an awl- or wart-shaped tip, is somewhat shortened 

 and compressed laterally. 



Abdomen very much lengthened Genus £cta<lilis Foerster. 



Abdomen not especially lengthened. 



Second ventral abdominal segment strongly compressed with 9 • 



Genus Sactogaster Foerster. 

 Second ventral abdominal segment not compressed. 



Genus Syiiopeas Foerster. 

 Scutellum not lengthened, semi-circular; either flat or convex. 



Scutellum quite flat Genus Anopedias Foer.ster. 



Scutellum not flat. 



Head cubical Genus Isocybiis Foerster. 



Head not cubical. 



