284 HYMENOPTEEA OF AMERICA. [PART I. 



mandibles, an arc or two spots on the summit of the clypens, a 

 dot on the front and another behind each eye, the border (retracted 

 in the middle) of pronotum, a spot under the wing, post-scutel, 

 often a dot at the wing scale, and the border of the first two 

 segments of the abdomen, of a whitish-yellow; the border of the 

 first segment widened on the sides ; often tri-emarginate. Wings 

 of a brown-violet; tarsi brownish. 



Var. a. Beneath the scape a ferruginous or whitish line; the 

 3d abdominal segment adorned with a whitish edging. 



b. Clypeus and antennae wholly black. 



c. Tibiae marked with white on their outer border (Illinois). 



% . Smaller. Clypeus polygonal, slightly prolonged at the end 

 and truncate, subbidentate, its color whitish, with the inferior 

 borders black; hook of the antennas great; on the scape a white 

 line. Mctathoracic ridges salient on the summit, terminated 

 behind the post-scutel by a more elevated pyramidal tooth. 



Var. The ornaments passing into sulphur-yellow. 



Bess. a. cliff. — This Odynerus is easily recognized by its whitish 

 ornaments. In likeness it resembles : — 



1. The 0. bidens and the Monobia 4-de??e, from -which it is 

 distinguished easily by its small size, by the absence of lateral 

 teeth on the metathorax, by the cribrose thorax, and the rugose 

 metathorax, etc. 



2. The 0. i-sectus, from which it separates itself by its livery 

 and its quite differently formed metathorax. 



3. The 0. leucomelas, from which it differs by the livery of 

 its abdomen, by the whitish band of its 1st segment, widened on 

 the sides, by its abdomen truncate, with a sharp ridge at the base; 

 by its metathorax with elevated borders; by its violet wings. 



4. The Ancistrocerus albophaleratus ; from which it differs by 

 its livery and by the absence of a suture on the first abdominal 

 segment. 



In the distribution of colors it approaches the 0. foraminatus 

 and allies. 



Bab. The United States. Carolina, Tennessee, Illinois (Kern 

 nicott), Florida (Norton), 8 ?, 11 %. 



