1*6 HYMENOPTERA OF AMERICA. [PART I. 



Abdomen wide and conical; the first segment short, as wide as 

 the 2d, elevated at the suture ; its superior surface often longi- 

 tudinally .striate along the suture ; the border of the segment 

 distinctly punctured ; that of the* 2d insensibly reflexed. 



Insect black, strongly mingled with yellow. Mandibles brown 

 at the extremity. Clypeus yellow, at times adorned with a little 

 brown dot. Antenna? black, with the scape yellow before and the 

 flagellum ferruginous beneath at its base. A spot on the front, 

 one behind each eye, a wide border on the prothorax, a spot 

 below the wing, wing scale, scutel post-scutel, two arcuate spots 

 occupying the angles of the metathorax, and a wide border on 

 every segment of the abdomen, yellow ; these borders regular; 

 that of the 1st segment joined to two oblique lateral spots; the 

 2d ornamented on each side by an oblique spot, sometimes 

 separated, sometimes confounded with the border. Anus yellow. 

 Feet yellow, thighs obscure at their base; coxae spotted with 

 yellow. Wings transparent, a little smoky along the side and 

 toward the end, with a light violet reflection. 



Var. a. Scutellum having but one yellow interrupted band. 



b. No yellow lateral spots on the 2d segment. 



c. The border of the 2d segment festooned in consequence of 

 the fusion with the lateral spots. 



d. The yellow ornaments passing into orange. 



%. Same size as the ?. Extremity of the antennas and their 

 hook ferruginous ; clypeus bidentate. Mandibles yellow. Scu- 

 tellum divided by a groove. Yellow ornaments narrower, often 

 interrupted on the scutel; lateral spots of the first two segments 

 small. Anus only spotted with yellow. (The border of the first 

 segments in general regular, only confounded on each side with a 

 yellow dot.) 



Var. Size small, length 11 mm. ; wing 8 mm. 



Bess. a. cliff. — This beautiful species is very distinct in its very 

 stubbed form, in its size, in its cubical and finely punctured 

 thorax, not cribrose with holes, in the exceptional width of its 

 yellow markings. It can, however, be confounded with the Ody- 

 nerus Catskillensis, from which it may be distinguished by the 

 yellow clypeus of the female, by the much richer ornamentation, 

 by the notably more stubbed form, and by the two oblique yellow 

 spots of the first segment which mingle themselves with the border; 

 by the elevated and truncate post-scutel and by its superior size. 



