372 IIYMENOPTERA OF AMERICA. [PART I. 



"9. Plead black, dilated ; posterior and anterior orbits, to the 

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

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

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

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

 stethidium black; collar and wing scale ferruginous; scutel with 

 two large yellow spots ; metathorax, 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." 



Hah. Missouri. 



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

 aztecus, but with a richer coloration. 



Gen. CTEx\OCHILlTS' Sattss. 

 Epipona Spin. — Pterochihis Sauss. — Ctenorhilus Sauss. Vespid. III. 323. 



Labial palpi pectinate as in Pterochilus. 



Mandibles rather short, nearly obliquely truncate, strongly 

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

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

 Eumenes. 



This genus represents the petiolate Pterochilus, and it bears 

 the same relationship to this genus as Eumenes to Odijnerus. 

 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 Zethvs 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 Zeihus 

 and Pterochilus. 



Ct. pilipalpws Spin.— Gracilis, capite magno, postice excavato ; 

 clypeo transverse,, apice tridentulato, fimbriato ; pronoto cristato-margi- 

 nato; scutellis pronn'nulis ; petiolo lineari, apice globoso-inflato ; clypeo 



Ktei,', xtevoj comb; p^et>o;, lip. 



