372 IIYMEXOPTERA OF AMERICA. [PART I. 



"?. Head black, dilated; posterior and anterior orbits, to the 

 emargination of the eyes, ferruginous; hypostoma, scapus of the 

 antennae, and mandibles, ferruginous ; flagellum black-brown ; 

 labial palpi testaceous, very long, ciliate with long hair, tbree- 

 jointed, terminate joint much compressed, flat, obtuse at the tip; 

 stethidium black; collar and wing scale ferruginous; scutel with 

 two large yellow spots; metatborax, with a transverse yellow 

 line, and at the base on each side, a large ferruginous spot; wings 

 a little fuliginous; pleura with a yellow spot beneath the superior 

 wings; feet ferruginous; tergum black, with five broad, bright 

 yellow, somewhat dentated bands, the posterior one abbreviated; 

 first and second segments each with a large ferruginous spot on 

 each side ; venter black, ferruginous at its base." 



Hab. Missouri. 



I do not know this species. It seems to be very near to PL 

 aztecus, but with a richer coloration. 



Gen. CTE^OCHII^US 1 Saoss. 

 Epipona Spin. — Pterochihis Sauss. — Ctenochilus Sauss. Vespid. Ill, 323. 



Labial palpi pectinate as in Pterochihis. 



Mandibles rather short, nearly obliquely truncate, strongly 

 indented. — Prothorax angulated. — Abdomen petiolate ; the first 

 segment quite contracted in its whole length into a petiole as in 

 Eumenes. 



This genus represents the petiolate Plerochilus, and it bears 

 the same relationship to this genus as Eumenes to Odynerus. 

 It presents, however, this difference ; the prothorax is angulated 

 and crested, which is not the case in Pterochilus. It has some- 

 what the facies of Zethus in the form of the petiole, the transverse 

 clypeus, the rather short mandibles (and the labial palpi, proba- 

 bly formed of three joints only, which I cannot verify). 



The Ctenochilus occupy an intermediate group between Zethus 

 and Pterochilus. 



Cto piMpalpils Spin. — Gracilis, capite magno, postice excavato ; 

 clypeo transverso, apice tridentulato, fimbriato ; pronolo oristato-margi- 

 nato ; scutellis promimilis ; petiolo linear!, apice globoso-inflato ; clypeo 



1 Kts;;, xt6vo; comb ; xe~>>o?, lip. 



