504 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 57. 



transversiy rugose; scutellum convex, not margined laterally; mesepis- 

 termim not especially lengthened; legs ratlier long, none of the parts 

 especially robust, posterior femora not dentate; abdomen polished, 

 without elevations or furrows, petiolate to subsessile, compressed api- 

 cally; hypopygidium in female large, vomeriform; ovipositor long, 

 compressed or subcompressed, acute at apex with a more or less dis- 

 tinct dorsal angulation some distance back from apex, lancets en- 

 closing lance laterally at extreme apex. 



KET TO THE HOLARCTIC GENERA. 



1 . Piopodeal spiracle round or long oval and placed near base of segment; last joint of 



hiud tarsus distinctly shorter than second; apical tergite elongate, prominent, and 

 more or less trowel-shaped ; clypeus distinctly separated from face medially ; malar 

 furrow obsolete; front and middle claws simple; nervelius strongly reclivous, 



broken far above middle Coleocentrus Gravenhorst. 



Propodeal spiracle long oval or slit-like and placed at about the middle; last joint 

 of hind tarsus distinctly longer than second; apical tergite not elongate; clypeus 

 usually not distinctly separated from face medially; malar furrow distinct; front 

 and middle claws usually finely bidentate at apex; nervelius perpendicular or 

 slightly reclivous, broken at or not far above middle 2. 



2. Abdomen very narrowly petiolate, first tergite much more than twice as long as 



wide at apex, the spiracles at about the middle; second recurrent vein antefurcal 

 or interstitial; front wings usually more or less infumate at apex; entire body pale 

 or contrastingly colored in black and yellow or whitish; antennae long and 



slender, usually annulated Arotes Gravenhorst. 



Abdomen rarely petiolate, and if so the spiracles of 1st tergite are far before middle; 

 if spiricles are in the middle the tergite is much broader; second recurrent post- 

 f ureal; front wings immaculate; head and thorax immaculate black, abdomen uni- 

 colored or bicolcred black and rufous; antennae short and stout, not annulated. .3. 



3. Wings with an areolet; front and middle claw simple; clypeus broadly subtruncate 



and reflexed at apex, without a median tooth or angle; malar space little more 

 than half as long as basal Avidth of mandible; sternauli practically absent; notauli 

 deep and meeting before the scutellum; propodeal carinae weak. 



Mesoclistus Foerster. 



Wings without areolet; front and middle claws bidentate at apex; clypeus truncate 



and at least angulate medially; malar space nearly or quite as long as basal width 



of mandible; steirnauli well defined 4. 



4. Notauli very weak, scarcely at all impressed; propodeal carinae weak; prepectal 



carina weak and terminating low down on pleura; first tergite nearly or quite as 

 wide at apex as long, the spiracles nearly in the middle. .Acoenites Latreille. 

 Notauli strong and complete, meeting some distance before scutellum; propodeal 

 carinae strong; prepectal carina very strong and reaching nearly to dorsal margin 

 of pleiura; first tergite nearly or twice quite as long as wide at apex, the spiracles 

 distinctly before the middle Phaenolobus Foereter {=^Chorischizus Foerster). 



Genus COLEOCENTRUS Gravenhorst. 



Coleocentrus Gravenhorst, Ichn. Eur., vol. 3, 1829, p. 437. Genotype.— Ich- 

 neumon excitator Poda. 



From all the other genera of the tribe this genus differs in the 

 basal position of the propodeal spiracle, the short apical joint of the 

 hind tarsus, tlie lodg terminal tergite, and the obsolete malar fm-row. 



