AMERICAN HYMENOPTERA. 197 



7. Postscutel black, scutel marked witli yellow 16. 



Postscutel not black, scutel black - 8. 



8. Posterior ocelli witbout tubercles between theru* 11. 



Posterior ocelli with tubercles between them 9. 



9. Clypeus bispinose, flagellum black vagiis Sauss. 



Clypeus bidentate, flagellum not black beneath 10. 



10. Ornaments often red, base of femora reddish OCiileiiK n. sp. 



Ornaments yellow, base of femora black illinoensis n. ap. 



11. Clypeus truncate Huoriiiis Say. 



Clypeus more or less emarginate and bidentate 12. 



12. Margins of segments 2 and 3 of abdomen reflexed fuiidalus Cr. 



Margin of segment 3 not reflexed 13. 



13. Margin of 2 not reflexed 15. 



Margin of 2 reflexed 14. 



14. Ornaments yellow, margin of 2 reflexed perpendicular to line of profile. 



peclestris Sauss. 

 Ornaments mostly red, margin of 2 not so strongly reflexed. 



fiiiKlatiformis n. sp. 



15. Segment 1 of abdomen red, ornaments more or less red . . -aiistrali^i u. sp. 

 Segment 1 black, ornaments yellow , pereiiiiis Sauss- 



16. Concavity of metathorax narrow aoolliiiiis Sauss. 



Concavity of metathorax broad ... zeiidaloides n. sp. 



FEMALES. 



Belongs to Stenodynerns 8. 



Belongs to Stenancistrocerus 1. 



1. Tubercles between posterior ocelli wanting 6. 



Tubercles present, less evident than in males 2. 



2. Ornaments mostly red 5. 



Ornaments yellow 3. 



3. No spots on segment 2 of abdomen fiilvipes Sauss. 



A spot on each side of 2 4. 



4. Clypeus coarsely punctured, bidentate bicoriiis n. sp. 



Clypeus less coarsely punctured, less bidentate llistrioualis n. sp. 



5. Clypeus coarsely punctured, bidentate, segment 1 of abdomen usually red, 



with anterior fac« and basal middle of superior face black. 



bifiircus n. sp. 



Clypeus less coarsely punctured, less bidentate, segment 1 of abdomen usually 



red, with base black liistrio Lei). 



6. Apex of clypeus emarginate, witii dentiform angles Msecularis Sauss. 



Apex of clypeus broad, distinctly truncate 7. 



7. Ornaments yellow clypeatu!« n. sp. 



Ornaments red fluridaiiiis n. sp. 



8. No tubercles between posterior ocelli 11. 



Tubercles present, less evident than in male 9. 



9. Clypeus rather strongly bidentate, large species vagus Sauss. 



Clypeus with faint dentiform angles 10. 



® Males of 0. pedestris sometimes show two small tubercles. 



TRANS. AM. ENT. SOC, XXVII. APRIL, 1901. 



