108 FAMILY EYANIID^. 



family. lu Fmius (Fig. 73) tlie base of the longitudinal part of 

 M has become interstitial with Ciu, crowding m-cu out of existence 

 and greatly reducing the size of the cells M3 and M4. In Pseudo- 

 fmius (Fig. 74) the condition is the same, except for an additional 

 step, the vein M4 being lost and cells M3 and M4 thus thrown together. 



The habitus is similar in all the species that I liave studied, the 

 proportions being always slender, the neck long, and the posterior 

 tibite very strongly clavate. But not in the genus Hyptiogaster, at 

 least not in H. humeralis, in which the form is stouter, the neck 

 short and the posterior legs stout ; the femora very stout, as though 

 for leaping ; the tibiae stout but not clavate ; the tarsi very short, 

 exclusive of the claw, less than one-third as long as the tibise, the 

 second and third joints being extremely short, much broader than 

 long, while the claw is quite large. The mouth parts are much ' 

 enlarged and used for sucking (Figs. 20-21). 



The claw (Fig. 43) is always simple ; the mouth parts are shown 

 in Figs. 20-23. 



An interesting character is found in the longitudinal folding of 

 the wings, as in the Vespoidea. Outside of these there is only one 

 other genus of Hymenoptera known to have this habit, namely 

 Leucospis, a Chalcid. 



A quite extensive account of the life history. of i^cen?<s (Gasterup- 

 tion) is given by Hoppner.* The genus is parasitic on the larvte of 

 aculeate Hymenoptera, and has been bred from Prosopis, Trypoxy- 

 lon, Osmia, Erlades, Odynerus, Colletes and Cemones. In the col- 

 lection of Cornell University is a specimen lacking an abdomen, but 

 probably F. incertus, bred from the nest of Passalvecus diHtinctus Fox. 



Only Fcenus occurs in tlie United States. 



TABLE TO THE GENERA OF FCENIN.E. 

 ] . In the front wings m-cu absent (Figs. 73, 74), the base of the longitudinal part 

 of M joining Cuj ; [Posterior tibiaj swollen and tlavate; habitus slen- 

 der, the neck and head usually long] \ '2). 



In the front wings m-cu present, the base of the longitudinal jiart of M being 

 removed from Cuj (Fig. 72) ; [Posterior femora and tibia? sometimes 

 much swollen but not clavate; the tarsi sometimes very short; joints 

 2-4 broader than long; habitus stouter, head and neck not elongate.]* 



Hyptiogaster Kieffer. 

 (Type Gasteruption antennale Schletterer). 



* Allg. Zeitschr. f. Entom., ix, p. 97, 1904. 



t The bracketed characters may not always hold true, but do in all the species 

 that I have seen. 



