18 



HYMENOPTERA OF AMERICA. [PART I. 



Eab. South America. Cayenne. 



This type has very ranch the form of Zethusculus, on the part 

 of its clypeus, and yel this form of clypeus appears in Z. qri-nipes. 



Division ZETHUSCULUS Sauss. 



(Sauss. Vespides, I, 15; III, US.) 



,ik1 abdominal segment subsessile, or briefly pedieulate (the 

 le having at mosl a quarter the length of the segment). 

 ngtheued, its inflation variable. 



Species small, ornamented with black and yellow. 



The in- ' : - group often have the clypeus armed with 



two little separated teeth; this part is in general moderately 

 rounded, but is at times lozenge-shaped, as in the division Eeros, 

 with the lateral angles sharp (Z. spinipes) ; the head and thorax 

 are cribrose with greal punctures, often rugose — the vertex offer- 

 in? frequently a corrugation which includes the antenna". The 

 thorax is generally short, and at times strongly ungulate; the 

 metathorax in particular is sometimes convex as with the true 

 Zethus, and at times becomes angulate. The lateral ridges are 

 very distinct and the Hanks beneath are smooth, compared with 

 the resl of the thorax. The posterior face of the metathorax is 

 convex, having two convexities or moderately flattened eleva- 

 tions, always velvety, less punctured than the rest of the thorax, 

 and in general covered with striae or wrinkles, silky upon the 

 dividing groove. Sometimes the posterior face of the metathorax 

 i.- concave and offers under the post-scutel a little excavation, 

 which recalls what one .-res among certain Odynerinse. One 

 often perceives, al ;o, two longitudinal carinas which start from the 

 angles of the post-scutel. 1 When these carinas become enlarged, 

 they produce ridges which border the cavity (Z. miniatus). 



The petiole is quite variable; sometimes the knob is elliptical 

 and depressed, bul more often the swelling is moderately cylin- 

 drical ; at firsl somewhal large, it then diminishes in size gradu- 

 ally to the extremity. In tine, it inclines to the campanular form, 

 whether lengthened pyriform, or clubbed and calling to mind the 



fiumenes or even tubular ; but the other characters always suffice 



1 When I say : metathorax bicarinate, it is meant that the carina? exist 

 en the ]>•• of tin' metathorax; for as the Intern! oh/<s or ridges 



found on all the species, I do not mention them in the descriptions. 



