IsORTH AMEEICAN HYMENOPTERA. 77 



Synopsis oT North American species of the 

 genus OX\BEL.LS. 



BY CHARLES ROBERTSON. 



In the preparation of this pai)er I am under obligations to Mr. 

 E. T. Cresson, who has kindly sent me for study the specimens con- 

 tained in the collection of the American Entomological Society. 



Unless otherwise stated, all notes on the time of flight and the 

 floral visits of these insects were made at Carlinville, Illinois. 



The type s]>ecimens of all of the new species, except the new 

 synonyms Packardii and suhulatus, will be found in the collection of 

 the American Entomological Society. 



The species may be characterized in the following manner : 



Squama tenniuatiug iu a curved point. 



Spine entire at tip, face with pubescence more or less silvery. 



Abdomen of male without lateral .spines ( % of si milis unknown) ; mandibles 

 black or with a tinge of rufous ; ornaments white, often more yellow^ 

 in male. 



Spot on tegulje, abdomen with basal spots separated 1. 4-notatus. 



No spot on tegulse, abdomen with continuous fascife 2. similis. 



Abdomen of male with lateral spines ( % of sericens unknown). 

 Densely and very coarsely punctured, mandibles black. 



Prothorax punctured, spine sharp pointed 3. subulatus. 



Vertex with median tubercle 4. cornutus. 



Less densely and coarsely punctured, mandibles yellow. 



Ornaments whitish, more yellow j_n male 5. I'ackartlil. 



Ornaments more yellowish, very pubescent 6. sericeus. 



Ornaments lemon yellow, small, 4-5V mm 7. lietus. 



Ornaments orange-yellow 8. lulvipes. 



Ornaments wanting, insect very black 9. niger. 



Spine eraarginate, face with golden pubescence 10. C'ressouii. 



Squama with lateral curved point, spine emarginate. 



Spots on first segment connected by narrow fascia 11. niexicauus. 



Spots on first segment widely separated. 



Front pi'otuberaut above, spine narrow; abdomen of male with four or five 



strong spines on each side, 10-spotted 12. frontalis. 



Front convex in profile, spine broad; abdomen of male with two or three 



weak spines, 4-8 spotted 13. einarginatns. 



Squama without a curved point, spine very short 14. Forbesii. 



