ODYNERtTS. 339 



?. Clypeus rather bicarinatc, polished, cribrose, truncate at, 

 tip. On the vertex a small impression. Prothorax squarely 

 cut, its angles not prominent. Metathorax rounded, punctured 

 a little less than thorax ; its cavity small, rounded, punctured. 

 The lateral ridges argenteous. Abdomen ovate ; nearly as 

 strongly punctured as the thorax ; the first segment cup-shaped, 

 a little margined ; the second rather wide, its margin having a 

 wide zone of more coarse punctures; not channelled, its extreme 

 edge very finely margined ; the 3d and 4th rather strongly punc- 

 tured. 



Black, silky, with the metathorax argenteous. A spot on 

 mandibles, a transverse spot on the summit of the clypeus, frontal, 

 ocular and post-ocular dot, and scape beneath, yellow. Anterior 

 margin of prothorax adorned with a moderately wide yellow 

 fascia, sometimes narrowed on the sides, bilobate in the middle. 

 A yellow fascia on post-scutel; wing scales ferruginous, margined 

 with yellow. All the segments of the abdomen regularly margined 

 with yellow (rather ochraceus); the first rather narrowly, the 

 second very widely; anus yellow at the extremity. Feet black; 

 wings subhyaline, nerves subferruginojs, the apex somewhat 

 smoky. 



Var. Metathorax black, or with two lateral yellow lines. 



% . Clypeus pyriform, yellow, terminated by two little triangular 

 teeth (sometimes blunted). A line on the mandibles and a 

 vertical line between the antenna?, yellow. Flagellum of the 

 antennae fulvous beneath. Yellow margin of prothorax narrow. 

 Metathorax a little more triangular. Second abd. segment not 

 so widely margined. Knees, tibiae, and tarsi yellow, obscure on 

 their posterior face. 



Var. Wing scales ferruginous. 



Var. 9 % . — a. Form narrow; anus black; margins of segments 

 3, 5, 6 narrow; anterior margin of prothorax narrow. 



6. Metathorax quite black. 



c. Margin of the abdominal segments wide; anus yellow (0. 

 Maya Sauss). 



d. A spot under the wing or no spot. 



e. The abdomen blacker, with argenteous reflection; its yellow 

 ornaments more golden. 



Bess. a. diff. — It differs from 0. mystecus by the livery of its 

 abdomen ; by its metathorax, not rough ; by the yellow band of 



