446 M. W. R. de V. GRAHAM 



Fore wing with postmarginal vein at most as long as the marginal vein, the 

 latter not noticeably thickened. Pronotum nearly always at least slightly 

 less wide than the mesoscutum. Right mandible, or both mandibles, with 

 four teeth. Scutellum discally with in most cases finer reticulation, rarely 

 as coarse as that of the posterior part of the mesoscutum .... 6 



5 (4) Marginal vein 11 to 1-25 times as long as the stigmal vein. Antenna with 



sutures of clava indistinct . . chalcidiphagus (Walsh & Riley) (p. 449) 



Marginal vein 1-25 to 1-65 times as long as the stigmal vein. Antenna with 



first suture of clava fairly distinct . . . apharetus (Walker) (p. 449) 



6 (4) Pronotum, in front of the collar, descending vertically with respect to the plane 



of the mesonotum and scutellum, the pronotal neck is therefore hardly visible 

 in dorsal view. Gaster black with metallic reflections, or at most reddish 

 at the base. Legs relatively stout. Fore wing often with a fuscous cloud 7 



Pronotum, in front of the collar, not descending vertically with respect to the 

 plane of the mesoscutum and scutellum, the pronotal neck at least partly 

 visible in dorsal view. Gaster often partly to wholly fulvous or yellow. 

 Legs sometimes slender. Fore wing immaculate ..... 8 



7 (6) Left mandible with three teeth, right mandible with four. Malar space half or 



slightly more than half as long as an eye ; breadth of oral fossa hardly 

 twice the malar space. Fore wing most often with a fuscous cloud below 

 the base of the marginal vein. Gaster not reddish-marked, on the average 

 relatively longer, normally 1-75 to 2-2 times as long as broad, rarely less. 

 Tibiae usually more or less infuscate medially . . luniger (Nees) (p. 450) 



Both mandibles with four teeth. Malar space one third or slightly more than 

 one third as long as an eye ; breadth of oral fossa 2-3 to 2-7 times the 

 malar space. Fore wing immaculate, sometimes faintly yellowish-tinged. 

 Gaster sometimes reddish basally, relatively short, 1 -4 to 1 -65 times as long 

 as broad. Tibiae yellow or testaceous . . . destructor (Say) (p. 450) 



8 (6) Left mandible with three teeth, right mandible with four. Gaster blackish 



with a weak metallic tinge, or at most somewhat reddish or testaceous at the 

 base ventrally. Antennal clava with a terminal stylus .... 9 



Both mandibles with four teeth. Gaster, except in arestor, in which the 

 antennal clava has no terminal stylus, at least partly yellow dorsally, often 

 mainly so both dorsally and ventrally . . . . . . . 10 



9 (8) Speculum of fore wing open below. Antennal scape reaching barely or only 



just to the lower edge of the median ocellus . . subniger (Walker) (p. 451) 



Speculum of fore wing virtually closed below. Antennal scape reaching 



about to the level of the middle of the median ocellus crassiceps Thomson (p. 452) 



10 (8) Antennal clava without a terminal stylus, merely conically pointed. Fore 



wing with postmarginal vein distinctly shorter than the marginal vein. 

 Gaster wholly metallic, or pale beneath at its base only. Legs relatively 

 stout, with femora more or less infuscate. Malar space barely or just one 

 third the length of an eye ..... arestor (Walker) p. 452) 



Antennal clava acuminate with a terminal stylus except in gibbiscuta, which 

 has the postmarginal vein virtually or quite as long as the marginal vein, 

 the gaster at least partly yellow dorsally (sometimes wholly yellow) and the 

 legs slender with wholly yellow femora. Gaster usually at least partly 

 yellow both dorsally and ventrally, rarely almost wholly dark in some 

 extreme forms of fulviventris. Malar space, except in gibbiscuta, about 

 half the length of an eye .........11 



11 (10) Postmarginal vein of fore wing virtually or quite as long as the marginal vein. 



Malar space only about one third the length of an eye. Scutellum strongly 

 convex, best seen in profile. Legs slender ; spur of mid tibia hardly half as 



