22 Key to Families of North A merican Insects. 



24. Basal joint of hind tarsi twice as long as the others united, the second with a 



long, spined process externally; abdomen greatly compressed, curved like a 

 pruning knife, much longer then the remainder of the body. (Ibalia.) 



IBALIID^E 



Basal joint of hind tarsi much shorter; second joint simple. (Andricus, Hol- 

 caspis, Neur6terus, Synergus) (PL 3, fig. 46) CYNIPID^E 



25. Antennae distinctly elbowed (PL 4, figs. 69, 70, 71). A few genera distributed 



among the families of Chalcidoidea. (See couplet 30.) 

 Antennae not elbowed (PL 5, fig. 85) 26 



26. Mandibles in a reversed position, the tips extending laterally and not meeting 



when closed (see couplet 18.) A few ALYSIID^E 



Mandibles attached normally 27 



27. Abdominal petiole expanded apically, not cylindrical (PL 5, fig. 85.) 28 



Abdominal petiole cylindrical (see couplet 22.) A few CYNIPOIDEA 



28. Ventral abdominal segments soft, with a median fold 29 



Ventral segments hard, without a fold. (See No. 19.) . . . .MYERSfflXE, part 



29. All dorsal abdominal segments free. (See couplet 20.) 



A few ICHNEUMONID^E 



Second and third dorsal segments usually immovably grown together. (See 

 couplet 21.) A few BRACONID^ 



30. Hind wings exceedingly narrow, linear, the base forming a long stalk; oviposi- 



tor issuing barely before the tip of the abdomen; antennae with the scape 

 not elongated, compressed, and without ring joint; very minute species 



with long wing-fringe. (Polynema, Gonat6cerus.) MYMARID^E 



Hind wings never very narrow, not linear or pedunculate at the base; ovipositor 

 issuing decidedly before the tip of the abdomen; antennae elbowed (PL 4, 

 figs. 69, 70, 71), with long scape and usually with from one to three ring 

 joints 31 



31. Tarsi five-jointed (rarely four-jointed or less in certain wingless males); axillae 



with their anterior margin usually straight and not produced anterior to the 



tegulae (PL 4, fig. 68); spur of front tibia strong 32 



Tarsi three- or four-jointed (five-jointed or heteromerous only in the females of 

 one or two genera) ; axillae produced forward, their front margin opposite or 

 anterior to the tegulae (PL 4, fig. 73); spur of front tibia usually weak. . . .42 



32. Head of female long, oblong, with a deep longitudinal groove above; front and 



hind legs very stout, middle ones very slender or aborted; males wingless 

 with short three- to nine-jointed antennae. Fig insects, mainly tropical. 



(Blastophaga, Eiseniella.) AGAONID.<E 



Of a different conformation 33 



33. Mesopleura with an oblique femoral groove or impression; spur of middle tibia 



not enlarged 34 



Mesopleura entire, always without femoral groove in the female and usually in 

 the male; spur of middle tibia usually very large and stout. (Eupelmus, 

 Anastatus, Encyrtus, Ageniaspis) (including EUPELMIDJE). 



ENCYRTDXaE 



