G. C. DAVIS. 227 



Tribe EXTBNTERINI. 



1. Teeth of niandibles of unequal length ; lower one larger and longer 2. 



Teeth of luandibles of equal length 3. 



2. Clypeus broadly truncate at apex ; tarsal claws not or very weakly pectinate 



at base Dolotoiims Holmgr. 



CUypeus broadly rounded at apex ; tarsal claws strongly pectinate to beyond 

 the middle » Anij^ooliiiion Foer 



3. Tarsal claws pectinate 4 



Tarsal claws not pectinate H- 



4. Margin of segment 1 hollowed out three times Trifamptuo* Fcier. 



Margin of segment 1 not hollowed out 5. 



5. Wings with an areolet *>• 



Wings without an areolet ■■ Eridolins Foer. 



6. Hiud tibise with a single small spur » MicTOpIeclron Foer. 



Hind tiiiiffi without a spur 7. 



7. Abdomen subpetiolate, basal segment distinctly broadened from the base 



toward the apex C'ieiiiscu- Curtis. 



Abdomen broadly sessile, basal segment is broadened immediately back of 

 base and almost insensibly from that to the apex 8. 



8. Superior median area without a distinct boundary or entirely wanting. 



Picroscopus Foer. 

 Superior median area distinctly bounded and as long, or longer than broad. 9. 



9. Metathorax oval, rarely spined ; scutellum oval or flat; base of second ab- 



dominal segment with oblique grooves Disiboriis Foer. 



Metathorax truncate posteriorly and spined at angles 10. 



10. Scutellum deeply and broadly excavated ; posterior median area very large, 



wider than high ; oblique grooves on second abdominal segment broad, 



rugose Excavariis Davis. 



Scutellum narrow, oval ; posterior median area rectangular : oblique grooves 

 scarcely indicated Andei'is Davis. 



11. Segment 1 broadened ear-like at base 12. 



Segment not broadened, ear-like at base Anecpliysiw Foer. 



12. Segment 2 at apex twice as bi-oad as 1 at apex ExyMtoii Schiodte. 



Segment 2 at apex scarcely once and a half as broad as 1 at apex. 



•■■ Acteiioiiy.v Foer. 



OEl-OTOiHUS Holmgren. 

 (Mouographia Tryphoniduin Suecise, p. 222, 18.56.) 

 Acrotomiis is a synonym. 

 Delotoiiiiis ruflis Prov. (Cteniscus), Faune Ent. Can. ii, 423. 



9.-4 mm. Rufous; head, except face and mouth, and thorax surrounding 

 scutellum, black: apex of abdomen dusky; trochanters and four anterior coxie 

 yellow; antennae long, dusky brown, reddish at base and apex; wings hyaline, 

 nervures and stigma brown; areolet triangular, sessile, oblique; abdomen sub- 

 sessile, slender at base; basal segment broadened toward apex and with median 

 groove. 



(Taken from Provaiicher's description). One speciiiien. 

 Tfie lower tooth of mandibles is considerably longer and larger 

 than the npper one. Type, coll. Quebec jNIiiseuin. 



TRANS. AM. ENT. SOC. XXIV. AUUU.ST, 1897. 



