PTEROMALIDAE OF N.W. EUROPE 185 



5 (4) Thorax weakly arched dorsally : in profile the scutellum appears virtually 



flat or at most weakly convex. Axillae and scutellum with delicate, en- 

 graved reticulation. All funicular segments, except sometimes the first, 

 transverse [Isoplata Forster) ........ 6 



Thorax moderately to strongly arched dorsally : in profile the scutellum 

 appears distinctly convex. Axillae and scutellum nearly always having 

 their reticulation at least slightly raised above the general surface. At 

 least some of the funicular segments are quadrate or longer than broad . 7 



6 (5) Scutellum about as broad as long, in profile appearing virtually flat. Pro- 



podeum strongly transverse, about five times as broad as its median length 



geniculatum (Zetterstedt) (p. 193) 

 Scutellum slightly longer than broad, in profile appearing slightly convex. 



Propodeum only about four times as broad as its median length . . 7 



7 (6) Scutellum weakly convex, in profile appearing only slightly curved ; scutellum 



and axillae with delicate, engraved reticulation. Propodeum medially less 

 than half as long as the scutellum, about four times as broad as long. 

 Otherwise much like geniculatum ..... sp. indet. A. (p. 193) 

 Scutellum moderately to strongly convex ; scutellum and axillae nearly always 

 with at least some of their reticulation slightly raised above the general 

 surface. Propodeum rarely less than half as long as the scutellum and 

 rarely so strongly transverse as in the above ...... 8 



8 (7) Lower edge of mandible (Text-fig. 147) excised in the middle, and with a 



conspicuous lobe at the base. Malar space almost half the length of an eye. 

 Length about i-8 mm. ; similar in general facies to alpestre (Ruschka) 



scaea (Walker) (p. 198) 



- Lower edge of mandible at most shallowly emarginate in the middle, and 



without a conspicuous lobe at the base. Malar space nearly always 

 relatively shorter .......... 9 



9 (8) Ventral opening of oral fossa (Text-fig. 148) large : the hypostomal carinae 



curving strongly, the greatest distance between them more than one third 

 the breadth of the head. In a ventral view of the head the hypostomal 

 carinae are clearly visible even when the maxillae and labium are in situ . 10 



- Ventral opening of oral fossa smaller, hypostomal carinae not curving strongly, 



the greatest distance between them at most one third the breadth of the 

 head. In a ventral view of the head, the hypostomal carinae lie close to the 

 maxillae and labium and are not readily visible . . . . . 13 



10 (9) Marginal vein of fore wing only about 1-15 to 1-2 times as long as the stigmal 



vein. Antennal scape reaching virtually to lower edge of median ocellus. 

 Breadth of oral fossa (Text-fig. 148) about 2-35 times the malar space, 

 the latter slightly more than one third as long as an eye 



genale (Thomson) (p. 197) 



- Marginal vein 1-4 to 1-65 times as long as the stigmal vein. Antennal scape 



not reaching the median ocellus . . . .....11 



11 (10) Combined length of pedicellus and flagellum 1 -3 to 1 -35 times the breadth of the 



head, flagellum relatively less stout ; proximal segments of funicle slightly 

 longer than broad ......... sp. indet. 



Combined length of pedicellus and flagellum i-i to 1-2 times the breadth of 

 the head, flagellum relatively stouter ; proximal segments of funicle 

 quadrate ............ 12 



12 (11) Breadth of oral fossa about twice the malar space . scot icum (Walker) (p. 196) 



- Breadth of oral fossa about 2-5 times the malar space . . . . sp. indet. 



13 (9) Gaster distinctly longer than head plus thorax, 2-2 to 3-3 times as long as 



broad ............ 14 



