[165] HYMENOPTERA 17 1 



7. Clypeus black 8 



Clypeus not black. 



Antennae 24-jointed, the flagellum ferruginous ; clypeus, mandibles, 

 except teeth, palpi at base, tegulae, a spot in front, apices of front 

 and middle coxae, all trochanters more or less, tibial spurs and the 

 ventral fold of abdomen, ivory or yellowish-white. Female. 



E. clypeatus. 



Antennae 23-jointed, the flagellum black ; clypeus and legs, except the 

 hind coxae, ferruginous ; palpi and tegulae pale yellow. Male. 



E. seldcrvice. 



8. Abdomen mostly red or segments i to 6 banded with red 12. 



Abdomen mostly black, with usually only the second and third 



segments red or red in part 9. 



9. Antennas 2i-jointed or less 10. 



Antennas 26-jointed. 



Third abdominal segment red or red in part, especially 

 basally, sometimes the apex of the second segment red. 

 All coxae black ; basal joint of trochanters, the femora more or less 

 and the hind tarsi black, rest of legs rufo-testaceous. 



E. rubrocinctus. 

 Antenna? broken. 



Second abdominal segment, except the extreme base, and the third 

 segment, except at apex, red ; legs, including coxae, fulvo-ferrugi- 

 nous. Female E. ungensis. 



10. Antennas 2O-jointed or less n. 



Antennae 21 -jointed. 



Second andthird abdominal segments red ; legs, including coxae, fer- 

 ruginous E.sarpedontis. 



1 1 . None in this section from Alaska. 



12. Antennas 28- jointed. 



Antennae not ringed with white E. ithacae. 



Antennae ringed with white E. concamerus. 



EXOLYTUS PERPLEXUS sp. nov. 



Male. Length 4 to 4.5 mm. Polished black, impunctate; an 

 annulus at base of first joint of the flagellum, sutures of trochanters, 

 knees, tibiae beneath sometimes but rarely, tibial spurs and the 

 extreme apices of the tarsal joints, testaceous. The antennae are 24- 

 jointed, the third joint the longest, a little longer than the fourth. 

 Wings hyaline, the stigma and veins dark brown, the costas, median 

 and submedian veins in the front wings toward base, and the subcostal, 



