266 HYMENOPTERA OF AMERICA. [PART I. 



very rugose, its posterior faee concave and striate; its borders 

 not trenchant but coarsely punctured, rugose, and forming on 

 each side a dentiform angle rather than a tooth ; its superior 

 ridges hardly indicated, especially upon the summit, where they 

 describe on each side a little arc, but without being at all termi- 

 nated by a pyramidal point. Abdomen silky; the 1st segment 

 bell-shaped, not being abruptly terminated anteriorly, but rounded, 

 so that its anterior and superior faces are not separated by a ridge. 

 Second segment short, having its border very strongly canali- 

 culate, a little reflexed and very coarsely punctured ; the canal 

 rugose, and slightly widened' angularly in the middle. Margin 

 of the following segment very coarsely punctured, but not cana- 

 liculate. 



Head black. Clypeus, mouth, and border of the orbits, ferru- 

 ginous. Antennas black, with the first three articles ferruginous. 

 Between their insertion a ferruginous triangle. Thorax black. 

 Prothorax, a spot under the wing, tegulae, scutelli, angles of 

 metathorax, and legs, ferruginous. Abdomen ferruginous ; all the 

 segments bordered with obscure yellow; the 1st and 2d having a 

 little of black at their base ; this color profoundly notched with 

 ferruginous, and forming on the 2d segment a triangle, and on 

 the 1st a lengthened spot in the form of a bottle, or variable. 

 These colors are in fact quite variable ; in certain specimens one 

 sees some yellow appear on the clypeus, on the border of pro- 

 thorax, on the post-scutel, and on the tibiae ; among other things, 

 the abdominal segments hardly offer a yellow cloud. Wings fer- 

 ruginous. 



%. Clypeus polygonal, as wide as long, truncate, not biden- 

 tate, ferruginous. Hook of the antennas ferruginous. 



War. The ferruginous parts of a pale red. Clypeus, mouth, 

 frontal spot, a line on the scape of the antennae, yellow. Ridges 

 of metathorax a little less effaced ; the canal of the border of 2d 

 segment very wide and shallow. (ATesothorax offering two 

 lateral red spots a little before the tegulas. Articles 2 and 3 of 

 the maxillary palpi slender.) Cordova. 



The maxillary palpi of this Odynerus have their last three 

 articles small, but not small enough to cause it to be placed in 

 the genus PJnjnchium, to which it bears, in fact, a resemblance. 



Hess. a. diff. — It is very near to the 0. Guerreri and Hidalgi 



