ODYNERUS. 217 



1. First abdominal segment tubercnlate before its groove. 



51. tuber culatus. 

 4, 4. First abdominal segment not tubereulate. 



56. humeralis, 

 3, 3. Antennae entirely rufous. 63. ruficollis. 



2, 2. Prothorax black or bordered with luteous. 



3. Antennae black on the superior face. 



4. Their first joint rufous. 57. Tarabucensis. 



4, 4. The whole antennae black above. 



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



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



6. Abdomen rather petiolate; hinder margin of prothorax 

 yellow ; 2d abd. segment not tubereulate beneath. 



48. arcuatus. 



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

 ^ low ; 2d abd. segment tubereulate beneath. 



55. veslitus. 

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



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



5. Metathorax without sharp edges, not bidentate. 



6. Small, post-scutel luteous ; clypeus J 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 anterioily 

 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 9 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. 



1 Wauting in some varieties. 



