ODYNERUS. 305 



2, 2. No erect spines on metathorax, behind the post-scutel. 



3. Scutel, metathorax, and first segment orange, wings ferruginous, 

 witli the apex brown. 115. Enyo. 



3, 3. Insect black, with yellow or luteous ornaments. 



4. Post-scutel black, truncate or crested; scutel adorned with 

 yellow. Small species very slender. 



5, Metathorax unarmed. 



6. Quite small ; antennae and pleurae maculate. 



14!). acolhuus. 



6, 6. Larger. Antennae and pleurae J immaculate. 



150. zendalus. 

 5,5. Metathorax having superiorly two small tubercles; quite 

 small species. 



6. Tubercles large, dentiform ; post-scutel truncate, not 



crested. 154. tepanecus. 



6, 6. Tubercles small. Post-scutel crested. 



7. Tubercles rounded, punctured; post-scutel crested ante- 

 rior^. 1 51 . na huus. 



7, 7. Tubercles sharp, compressed, very small. 



8. Post-scutel crested anteriorly. 152. olmecus. 

 8,8. Post-scutel crested posteriorly. 153. ckichimecus. 

 4,4. Post-scutel triangular or not distinctly truncate, generally 

 with a yellow fascia. 



5. Scutel and post-scutel orange. 142. columbaris. 

 5, 5. Scutel always black. 



6. Post-scutel crested, yellow. 124. Xantianus. 



6, 6. Post-scutel not crested. 



7. Post-scutel black. 



8. Thorax quite black. 



9. Only the first segment margined with yellow. 



132. Nortonianus, var. 



9, 9. Segments 2-5 margined with yellow. 



140. similis. 

 . o, 8. Thorax adorned with yellow. 



9. Only the first segment margined with yellow. 



132. Nortonianus. 

 9, 9. The first two segments adorned with yellow. 

 10. Second segment with two yellow spots. 



132." Nortonianus. 

 10, 10. Second segment without yellow spot. 



144. coyotus. 



7, 7. Post-scutel adorned with yellow ; the 2d segment mar- 



gined with yellow. 

 8. Anterior margin of prot borax adorned with yellow, 

 not its posterior margin. 

 9. Margin of 2d segment very strongly canaliculate 



and reflexed. 118 " J tn!l ecus. 



120. I? Toas. 

 20 



