PTEROMALIDAE OF N.W. EUROPE 383 



183 (182) Propodeum with a moderate-sized reticulate nucha, whose length is about 



one third that of the median length of the propodeum ; antennae inserted 

 about level with the ventral edge of the eyes, the head somewhat protuber- 

 ant at level of antennal toruli ; mesoscutum and scutellum, at least 

 mainly, with delicate engraved reticulation NASONIA Ashmead (p. 779) 



Either the propodeal nucha is a narrower weakly sculptured transverse strip 

 or ridge ; or the antennae are inserted well above the level of the ventral 

 edge of the eyes ; or the reticulation of the mesoscutum and scutellum is 

 slightly raised above the general surface . . . . . .184 



184 (183) Propodeum with a moderate-sized reticulate nucha, its length one third to 



half that of the propodeum ; antennae inserted well above the level of the 

 ventral edge of the eyes . . . . . . . . .185 



Propodeal nucha nearly always represented merely by a transverse ridge or 

 narrow strip, which is aciculate or smooth ; but if the nucha is rather 

 more distinct then the antennae are inserted about level with the ventral 

 edge of the eyes . . . . . . . . . .186 



185 (184) Gena with a hollow above the base of the mandible, extending fully one 



third up the malar space ; marginal vein of fore wing somewhat thickened 



METASTENUS Walker (p. 829) 

 Gena without a hollow above the base of the mandible ; marginal vein of 



fore wing not thickened .... TRICOLAS Boucek (p. 563) 



186 (184) Gena with a large hollow above the base of the mandible ; stigma of fore 



wing (Text-fig. 319) rather large, subcircular ; first funicular segment 

 obviously longer than broad . . PSEUDOCATOLACCUS Masi (p. 694) 



Gena without a hollow. Stigma of fore wing smaller, tending to be oval or 



oblong ; first funicular segment often quadrate or transverse . . .187 



187 (186) Tip of hypopygium situated near apex of gaster, which in dorsal view 



appears blunt, the tips of the ovipositor sheaths rounded, and is hardly 

 longer than the thorax ; propodeum without plicae ; antennae inserted 

 somewhat above level of ventral edge of eyes. Head distinctly broader 

 than thorax, rather thick antero-posteriorly. Both mandibles with three 

 teeth KARPINSKIELLA Boucek (p. 632) 



- Tip of hypopygium remote from apex of gaster except in some Psilonotus and 



Mesopolobus, in which the gaster is pointed or acute apically with tips of 

 the ovipositor sheaths pointed, the gaster is at least somewhat longer than 

 the thorax, the propodeum has plicae at least sharp posteriorly, and the 

 right mandible has four teeth ; often also, the antennae are inserted at or 

 slightly below the level of the ventral edge of the eyes . . . .188 



188 (187) Hypopygium very long, its tip situated at least at three quarters the length 



of the gaster, or even beyond . . . . . . . .189 



- Hypopygium shorter, its tip situated at most a little more than half way along 



the gaster. ........... 190 



189 (188) Anterior margin of clypeus incised medially. Marginal vein of fore wing 



at most i-6 times as long as the stigmal vein ; postmarginal vein nearly 

 or quite as long as the marginal vein . PSILONOTUS Walker (p. 625) 



Anterior margin of clypeus truncate or shallowly emarginate. Marginal vein 

 of fore wing sometimes twice, or rather more than twice, as long as the 

 stigmal vein ; postmarginal vein sometimes distinctly shorter than the 

 marginal vein MESOPOLOBUS Westwood (p. 638) 



190 (171) Thorax distinctly flattened dorso-ventrally ; scutellum in profile appearing 



flat or virtually so, at least very slightly broader than long ; third anellus 

 of antenna usually about twice as broad as long or more. Either the 

 mesopleuron is entirely reticulate ; or the ovipositor sheaths are far 



