184 HYMENOPTERA OF AMERICA. [PART I. 



border upon segments 2-5 of the abdomen, knees, tibiae, and 

 tarsi yellow ; the first segment of the abdomen having its border 

 widened upon the sides, or rather, confounded with two lateral 

 spots ; border of the 3d much narrowed. Wings transparent, 

 bnt washed with brown-violet especially along the borders. 



Var. Clypeus black with four yellow spots, segments 4 and 5 

 of the abdomen with no yellow border. 



% . Clypeus emarginate, yellow ; mandibles yellow. 



I possess a male very closely allied to A. unifasciatus %, 

 having also the margins of the 2d and 3d segments sinuous and 

 coarsely punctured. But it differs from this species in the smaller 

 hook of the antennae, in the metathorax, wholly rugose ; even on 

 its concavity, which is less defined and not striate ; in the first 

 abdominal segment, which is parted by a quite strong longitudinal 

 groove, and in the 2d segment more compressed at its base. It 

 has the same markings, unless the prothorax has a little less of 

 yellow in the middle. As this % has the metathorax rounded and 

 the wings slightly washed with brown, it seems that it cannot 

 but belong to the 0. campestris, unless it represents a species 

 which may have escaped us. 



It differs sometimes from the 0. campestris in its scutellum 

 deprived of spots and in the groove of the first segment which 

 approaches to it, as well as the smallness of the antennary hook 

 of the Symmorphus. 



Bess. a. diff. — This species has the appearance of the 0. 

 parietum. It can be confounded not only with the Anciztrocerus 

 of this group, but with different Odyneri, properly speaking. 



It differs from the 0. unifasciatus in its more stubbed form, its 

 less violet wings, the less upturned border of the 2d abdominal 

 segment, and in its livery, more rich in yellow (spot beueath the 

 wing, spots on the scutellum, etc.) ; from the 0. capra in its 

 metathoracic excavation without border, in its smaller size, its 

 more obscure wings, and the strong rugosities of the border of 

 the 2d and 3d segment, etc. ; from the 0. Spinolse, in the same 

 characters, except that the wings of this last species are darker. 



Hab. The United States. Pennsylvania. Illinois. Carolina. 

 Connecticut (7 ?). 



26. .4. tir&erculiceps Sattss. — Niger, gro??e punctatus, piloso-velu- 

 tinus; rnandibulis, clypeo, oculorum marginilms, pedibus, pronoto, 

 tegalis, Bcatellis, macalis sabalaribus et metanoti. rufis ; antennis runs, 

 superne apicem versus nigris ; abdoinine rufo, segmentis flavo uiargi- 



