252 IIY.MENOPTERA OF AMERICA. [PART T. 



13, 13. Edges of the concavity of metathorax 



more blunted. 105. molest us. 



12, 12. Seutel black. 



13. Fascia of the first abd. segment narrow; 



ornaments pale. 103. leucomelas. 



13, 13. Fascia of the first abd. segment wider, 



,, 102. I foraminatus. 



yellow. <. J 



107. (Jlavo/iictus. 



10, 10. Second segment with lateral yellow maculae oi 



fascia. ]04. blandus. 



8, 8. Superior angles of metathorax not produced behind 



the post-scutel or scarcely produced. 



9. Second segment without lateral yellow spots. 



10. Metathorax strongly excavated, rough ; all the 



segments margined with yellow. 



105. iiialestus. 



10,10. Metathorax not strongly excavated, not rough; 



2, 3 segments margined with yellow. 



109. Romandinus. 



9, 9. Second segment with lateral yellow spots or fasciae. 



104. blandus. 



Descrijition of the species. 



Section I. — Post-scutel sharply truncate; its transverse edge 

 often crenulate. Abdomen conical or ovate-conical; the 

 second segment not strangulated at base; the first segment 

 including it very naturally. 



1. Posterior plate of metathorax an gulate, forming on each side 

 a lateral dentiform angle. (Thorax square, angulate, poste- 

 riorly wide, uot contracted. Abdomen very conical.) 



A . Concavity of the metathorax polygonal, margined with straight 

 or arcuate ridges, wh ich form at their meeting a sharp a mile. 

 The superior lateral edges superiorly terminating in a tooth 

 or eminence, separated from the post-scutel by a deep fissure, 

 or by a voir It. 



These teeth ore more distinct in the males than in the females, 

 sometimes obsolete in the females. 1 Comp. Sec. B. 



a. Ridges of the. metathorax very salient ; its posterior fare excavated. 

 * Posterior margin of 2d and 3d abdominal segments reflexed. 



$2. O. Ili»la.la;a Sahss. — Niger, crasse oribri instar punctatus ; clypeo 

 in utroque sexu truncate-; metanoto valde concavo, biangulato, canthis 



1 Principally in Odyn. Doscii and dorsalis. 



