70 BULLETIN 66, UNITED STATES NATIONAL MUSEUM. 



4. The tribe is a division of convenience at present, separating 

 genera confined to a single family of hosts. 



5. The genera are based on the characters of the mouth parts, 

 genitalia, wing venation, and thoracic structure. They are found to 

 be confined to single genera of hosts. 



6. The species are based on proportionate lengths of mouth parts, 

 width of head, wing venation, the shape of the cedeagus, position of 

 genital pore and coloration in the male; and on the shape of the 

 cephalothorax and mandibles in the female. They are as a rule 

 confined to single species of hosts. 



MALES. 



Table of superfamilies and families based on males. 



Winged, elytrophorous. 



Tarsi with five joints and two tarsal claws Superfamily Mengeoidea Pierce. 



Tarsi with four joints; antennae with third joint laterally produced. 



Superfamily Xenoidea Pierce. 



Tarsi with three joints Superfamily Halictophagoide a Pierce. 



Tarsi with two joints Superfamily Elenchoidea Pierce. 



Superfamily MENGEOIDEA Pierce. 



Antenna' seven-jointed, third and fourth joints laterally produced. 



I. MENGEiDiE Pierce. 

 Superfamily XENOIDEA Pierce. 



Antenna) seven-jointed, fourth joint short, others beyond elongate. 



II. Myrmecolacid^e Pierce. 

 Antenna? six-jointed, the last three joints not much surpassing the flabellum of 



the third Ill- Stylopid.e Kirby. 



Antennae five-jointed, with fourth joint very short, and fifth elongate. 



IV. Hylechthrid^e Pierce. 

 Antenna? four-jointed, with flabellum of third, and fourth joint elongate, subequal. 



V. Xenid/E Semenov. 



Superfamily IIALICTOPHAGOIDEA Pierce. 



Antenna? seven-jointed, with the third, fourth, fifth, and sixth joints laterally 

 produced, and the seventh elongate VI. Halictophagid;e Pierce. 



Antenna? four-jointed, with the flabellum of the third, and fourth joint elongate, 

 subequal VII. Dioxocerid^e Pierce. 



Superfamily ELENCHOIDEA Pierce. 



Antenna? five-jointed, with the third laterally produced, and the fourth and fifth 

 elongate VIII. Elenchidje Pierce. 



Table of genera. 



1. Family Mengeid.e Pierce. 



Mandibles, maxilla? and maxillary palpi present, labial palpi absent; wings having 

 eight primary veins from base, with one distal unattached vein between subcosta 

 and radius and with the first and second anal apically united 1. Mengea Grote. 



Mandibles apparently absent; wings with seven primary veins from base, with one 

 distal detached vein beyond the tip of the radius, another above the radius, medius 

 with two superior branches; third anal lacking 2. Trioxocera, new genus. 



