ODYNERUS. 217. 



1. First abdominal segment tuberculate before its groove. 



51. tuberculatus. 

 4, 4. First abdominal segment not tuberculate. 



56. humeralis. 

 3, 3. Antennae entirely rufous. 63. rujicollis. 



2, 2. Prothorax black or bordered with luteous. 



3. Antennae black on tbe superior face. 



4. Their first joint rufous. 57. Tarabucensis. 



4, 4. Tbe whole antennas black above. 



5. The 2d abd. segment tuberculate above. 49. excipiendus. 



5, 5. The 2d abd. segment not tuberculate above. 



6. Abdomen rather petiolate ; hinder margin of prothorax 

 yellow ; 2d abd. segment not tuberculate beneath. 



48. arcuatus. 



6, 6. Abdomen more sessile ; anterior margin of prothorax yel- 



low ; 2d abd. segment tuberculate beneath. 



55. vestitus. 

 3, 3. Antennae rufous, or black only at the extremity. 



4. Second abdominal segment tuberculate beneath, at its base. 



5. Metathorax without sharp edges, not bidentate. 

 6. Small, post-scutel luteous ; clypeus $ black. 



52. tuberculiventris. 



6, 6. Larger, post-scutel black. 



7. Two luteous bands on the abdomen.' 



8. The hinder margin of the prothorax bordered with 

 luteous; clypeus 9 black. 65. vespiformis. 



8, 8. Prothorax not margined posteriorly with luteous. 



9. Abdomen rather petiolate, the 1st abd. segment 

 much narrower than the 2d ; prothorax anteriorly 

 margined with luteous. 54. labiatus. 



9 9. Abdomen sessile ; the 1st abd. segment sessile, 

 wide ; prothorax black. 64. Maypinus. 



7, 7. Only one luteous band, placed on the 1st segment; this 

 as wide as the 2d, sessile. 61. Antucensis. 



5, 5. Metathorax sharp, biangulate. 62. Chiliotus. 



4, 4. Second abdominal segment without distinct tubercle beneath. 



5. Clypeus ? rufous. 53. Molina. 

 5, 5. Clypeus 9 black. 



6. Pronotum and segments 1, 2, margined with luteous. 



50. subpetiolatus. 



6, 6. Only the first segment margined with luteous. 



58. albocinctus. 



» Wauting in some varieties. 



