AKT. 16 NORTH AMERICAN ICHNEUMON-FLIES CUSHMAN 15 



Except for its broader temples and hyaline wings it differs from 

 agenioides Viereck markedly only in its much more slender body and 

 I suspect it is the male of that species. The temples are about half 

 as long as shortest diameter of eye ; the thorax about three times as 

 long as deep with the propodeum sloping very gradually to apex; 

 the first tergite is fully three times and the second nearly four times 

 as long as broad at their junction ; the hind coxae are very long and 

 slender ; and the antennae without a white annulus. 



Genus LISTROGNATHUS Tschek 



Listrognathus Tschek, Verh. Zool.-bot, Ges. Wien, vol. 20, 1870, p. 153. Geno- 

 type. — Listrognathus cornutus Tschek. 



Mcsostenoideus Ashmead, Proc. U. S. Nat. Mus., vol. 23, 1900, p. 45. Oeno- 

 typc. — Mesostcntis alhomamilatMS Cresson. 



Idstrognathus (Tschek) Cushman, Journ. Wash. Acad. Sci., vol. 15, 1925, p. 

 390. 



Viereck's synonymizing of Mesostenoideus with Polycyrtus Spi- 

 nola is obviously incorrect, as I have previously pointed out. 



As I have shown in the reference cited above the type of Meso- 

 stenoideus will not run to that genus in Ashmead's key because of 

 the frontal horn. 



Quit6 as characteristic of this genus as the frontal horn is the 

 coarse, dense abdominal punctuation. 



Temples strongly, obliquely narrowed; frons usually with a dis- 

 tinct horn, rarely with only the trace of such a horn; eyes parallel 

 Avithin or nearly so, clypeus convex, usually very strongly elevated, 

 at base, transversely impressed at apex; malar space long; occipital 

 carina usually very prominent behind cheeks ; hypostomal carina very 

 high; antennae long, slender, flagellum in female slightly thickened 

 and flattened below toward apex, first joint much longer than second, 

 which is slightly longer than third, fourth much shorter than third, 

 in male flagellum tapering beyond middle, joints gradually shorter 

 from base. Thorax stout, about twice as long as deep and slightly 

 deeper than broad, densely and coarsely punctate with propodeum 

 usuall}' more or less rugose; upper margins of jDronotum swollen 

 and anteriorly carinately angled by the epomia; notauli distinct and 

 complete, scutcllum margined only at extreme base, convex, polished 

 and at most sparsely punctate; sternauli deep anteriorly, obsolete 

 posteriorly; propodeum with both transverse carinae and frequently 

 with median carinae more or less indicated between the transvei-se 

 carinae, apical carina sometimes obsolete medially, apophyses well 

 developed or indicated by strong elevations in apical carina, spiracles 

 elongate or oval; areolet subquadrate or subpentagonal, closed, re- 

 current near apex; nervulus antef ureal; postnervulus broken below 



