254 HYMENOPTERA OF AMERICA. [PART I. 



brown with violet iridescence, or fusco-violaceous ; the base paler 

 or a little ferruginous. 



Var. Prothorax often with some rufous color; the yellow 

 changing to fulvous. 



%. A little smaller. Macula? of metathorax larger; its supe- 

 rior ridges very salient, more arcuate, terminated superiorly by a 

 sharp tooth. Mandibles and clypeus yellow; this last polygonal, 

 wider than long; the angles of its inferior wide margin somewhat 

 toothed, the inferior part not prolonged as in 0. arvensis. 



Mexican variety ?. — Insect rufous and black. Head black; 

 mandibles, clypeus, margins of the orbits complete or interrupted 

 at the vertex, a spot on the forehead, and at base of antenna?, 

 rufous; prothorax, tegulae, a spot beneath them, rufous; scute] 

 rafous, notched, with black at base; their margins all yellow; 

 the margin of the first segment widened on the sides. Anus 

 yellow. Feet rufous, varied with yellow. Wings smoky, mixed 

 with ferruginous (0. Eidalgi Sss., 1. c). 



Var. Clypeus, scape of the antennas, and forehead, etc., varied 

 with yellow. 



%. Mandibles, orbits, a triangle on the forehead, a line on the 

 scape of the antennae, yellow; flagcllunr often ferruginous beneath ; 

 the hook ferruginous. Margin of prothorax, scutel, a spot under 

 the wing, and tibiae, often yellow. 



Eess. a diff. — This species is peculiar in having its first segment 

 sharply truncate in a right or even more acute angle. It differs 

 from the 0. Boscii and arvensis in its reflexed 2d and 3d abdo- 

 minal segments, its more sharply truncate 1st segment; in its 

 more elevated metathoracic post-scutellar eminences, its more 

 truncate clypeus. 



'I'he type (northern variety) differs from 0. Boscii in its yellow 

 post-SCUtel and black scutel. 



The Mexican (rufous variety) recalls 0. Guerreri and Iturbidi. 

 It differs from the first in its form and its not bidentate post- 

 scutel; from the second in its metathorax, superiorly very sharp, 

 in the reflexed margin of the 3d segment, the abdomen being 

 sharply truncate at base, not rounded, etc. 



Hab. United States. New York. Louisiana (E. Norton). — 

 The temperate part of Mexico. I caught 2 9, 1 £, var., in the 

 hot part of the province of Mexico, near Cuautta and Cuerna- 

 cava. Tamaulipas 1 9. 



