328 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 58. 



carinae of mesoscutum strong posteriorly and extending more or less 

 on to scutellum, the latter broad and weakly convex; mesoplural fur- 

 row curved or straight, not angulate opposite the punctiform fovea; 

 propodeum in profile declivous from near base, with or without closed 

 areas (in Holarctic genera without) ; legs usually stout, apical tarsal 

 joint long, curved, claws simple, in female sometimes with basal tooth 

 on some or all legs; wings with areolet always present, oblique quad- 

 rangular, nervellus reclivous and broken far above middle or the 

 submediella is interstitial with its upper extremity; abdomen sessile, 

 broadly fusiform, depressed; first tergite broad and with strong dor- 

 sal carinae, the anterior basin deeply concave; middle tergites trans- 

 verse to quadrate, lateral elevations weak or absent; ovipositor 

 short, stout, cylindrical, awl-like, usually straight, though sometimes 

 sharply decurved at extreme apex, the lance dorsally without sub- 

 apical notch or angulation, either flattened at apex or with its dorsal 

 margin decurved, the ventral margin of lancets curving upward 

 toward apex, the extreme apex rather obtuse. 



The robust form, with the rather small, almost lenticular head; the 

 short pronotum, which places the head close against the prescutum; 

 the stout, ovate thorax; the mesoscutum, which, even when the 

 notauli are strong, can hardly be said to have its anterior margin 

 trilobed; the sloping propodeum; stout legs; broad, depressed abdo- 

 men; and short, thick, cylindrical ovipositor combined produce a 

 habitus that once learned is very easy to recognize. 



The insects of this tribe are most likely to be confused with the 

 Ichneumonini, though it is doubtful if the two tribes are very closely 

 related. Certain of the exotic genera, notably Xanthopimpla Saus- 

 sure, approach the Theroniini in some of their characters, especially 

 in the areolation of the propodeum, and this tribe is probably the 

 closest relative of the Ephialtini. 



The two genera found in the restricted region embraced in this 

 paper are very readily distinguished by the characters used in the fol- 

 lowing key: 



KEY TO NORTH AMERICAN GENERA. 



Radiiis originating from beMnd middle of stigma; face usually strongly, densely 

 punctuate and usually wider than long, without orbital maculation, in male not 

 different from female; scutellum and postscutellum usually immaculate apically; 

 ovipositor straight at tip; claws in female (except sometimes the front ones) 

 without basal tooth; first tergite longer than second Ephialtes Schrank, 



Radius originating at or before middle of stigma, face polished, weakly, sparsely 

 punctate and usually longer than wide, with yellow orbital maculation, the latter 

 in male frequently embracing the entire face; scutellum and usually postscutellum 

 maculate apically; ovipositor abruptly decurved at tip; claws in female (at least 

 front and middle ones) with basal tooth or lobe; first and second tergites 

 subsequal in length Apechthis (Foerster). 



