i 4 M. W. R. de V. GRAHAM 



Mid tarsi not thus thickened, without a double row of short thick spines 



beneath. Mesepisternum, except in a few Aphelinidae, not evenly convex, 



but having a femoral groove. Mid coxae ventrally touching the trochan- 



tinal lobes, without a membranous area at their bases .... 9 



9 (8) Antennae with six to eight segments ; pronotum not large, shorter than the 



mesoscutum APHELINIDAE (part) 



- Either the antennae have 11 to 13 segments ; or else the pronotum is large, 



longer than the mesoscutum .... PTEROMALIDAE (part) 



10 (3) Females only : tarsi heteromerous, fore and hind tarsi with five segments, 



mid tarsi with four segments . . . . ... .11 



- Females and males : tarsi not heteromerous . . . . . . 12 



11 (10) Antennae with twelve to thirteen segments. Fore wing (Text-fig. 66) with 



postmarginal and stigmal veins well-developed. Moderate-sized species, 

 length 2-0 to 3-5 mm. (Macromesus only) . . . PTEROMALIDAE 



- Antennae with eight segments. Fore wing : postmarginal vein absent or 



rudimentary, stigmal vein short (much as in Text-fig. 31). Minute species, 

 length 0-5 to o-8 mm. (some Encarsia) ..... APHELINIDAE 



12 (10) Tarsi with three segments. Small to minute species, length 0-3 to 1-4 mm. ; 



antennae with only five to eight segments and usually very short ; hairs of 

 fore wing often in longitudinal lines . TRICHOGRAMMATIDAE (part) 



Tarsi with four or five segments. Species often larger ; antennae often with 

 a greater number of segments ; hairs of fore wing rarely arranged in longi- 

 tudinal lines ........... 13 



13 (12) Tarsi with four segments ......... 42 



- Tarsi with five segments .......... 14 



14 (13) Mid coxae (Text-fig. 9) inserted about level with the middle of the mesepi- 



sternum, or even anterior to this, the mesosternum being very short ; mes- 

 episternum enlarged and at least partly covering the mesepimeron, convex, 

 without a femoral groove ; mid tibiae with a very thick apical spur ; mid 

 tarsi thickened proximally, at least their first segment with two rows of 

 short stout spines beneath. 



Notauli usually absent, occasionally present or even complete but in 

 such cases very superficial. Metapleuron often very narrow or invisible. 

 Last tergite of gaster often more or less V-shaped . . . ENCYRTIDAE 



Mid coxae (Text-figs. 10, 12, 15, 17, 20, 24, 26) inserted behind the level of the 

 middle of the mesepisternum. Mesepisternum, except in most female and 

 some male Eupelmidae, and a few aberrant species of other families, 

 neither enlarged nor evenly convex, but having a femoral groove. Mid 

 tibial spur and mid tarsi, except in most Eupelmidae, not thus modified . 15 



15 (14) Mid tarsi thickened proximally and tapering distally, their first segment, and 



usually some of the following segments, with two rows of short stout spines 

 beneath ; mid coxae separated from the trochantinal lobes of the meso- 

 sternum by a membranous area (Text-fig. 11, membr.) which allows the 

 coxae to be swung directly forwards ; spur of mid tibia thick ; mesepi- 

 sternum (except in Oodera) greatly enlarged, evenly convex and without a 

 femoral groove, though separated from the mesosternum by a linear suture, 

 see Text-fig. 10. Pronotum often divided longitudinally down the middle, 

 by a groove, a membranous line, or a carina. Postspiracular sclerite (Text- 

 fig. 10) often longer than high, tending to be convex, sometimes free 

 ventrally and overlapping the mesepisternum somewhat. Propodeum 

 nearly always shorter medially than at the sides, sometimes nil medially ; 

 its hind margin being deeply, almost semicircularly, excised. Antennae of 



