Fossorial Uymenoptcra of North America. 433 



OXYBELUS, Latr. 

 Orybelus, Latr., Hist. Nat. xiii. (1805). 



% 9 . Head short and broad, less than half as broad as long; front 

 as broad below as above; clypeus with a narrow basal elevated ridge; 

 antennae short, thickening towards the end, bent as in Crabro, second 

 joint moderately long, thickened, third conical; mandibles narrowing 

 rapidly, on the outer third not toothed ; thorax globular, prothorax 

 short and broad ; the scutelluui is very short linear, transversely appres- 

 sed to the meso-scutum and much raised from the scutum, somewhat an- 

 gulated in front; mesothorax angulated in front; scutum shorter than 

 broad, somewhat rounded below; scutelluui sublimate, half as long as 

 broad. Scutelluui with a lateral membranous, triangular, acute ap- 

 pendage, which is ciliated within ; propodeum nearly as long as broad, 

 rapidly narrowing towards the insertion of the abdomen, with a basal 

 hollow spine. The tergum is margined with a raised ridge, and a 

 parallel ridge within encloses the triangular area. 



The middle coxae are very much shorter than the hind pair. Tro- 

 chanters nearly twice as long as broad. Legs stout; fore femora 

 swelled; fore tibia) slender, with a row of setae, and a large apical 

 spur. The tarsi are long, all the joints with terminal setae, 1st and 2d 

 joints with spine-like setae without; hiud tibiae with several rows of 

 setae; spurs long and slender; 1st joint equal to the length of the 2d, 

 3d and 4th joints; pterostigma narrow, costa within not thickened. 

 Primaries broad, outer margin straight; the 2d costal space is broader 

 than in Crabro, and the subcostal uervure is very distinct beyond it. 

 The lower side of the 1st subcostal space is obsolete, the space not be- 

 ing oblong but irregular, since the inner side of 2d costal space is 

 shorter. The 2d submedian space is not more than half as broad as 

 long, and the inner margin is indented at the termination of the in- 

 ternal vein. Secondaries broad, broadly lobed near the base. 



Abdomen cordate, being stout and broad, convex beneath, shorter in 

 9 , the base flattened and very slightly excavated ; coloration black, 

 abdominal spots on the side; the short, broad body, short antennae, 

 short spherical thorax, square in front, and bulging out at the sides, 

 the cordate abdomen, and broad, flattened first joints distinguish this 

 genus. The % is half the size of 9 , but the two sexes differ very 

 slightly otherwise, no anal stylets in % apparent. 



Synopsis of the Species. 



A. Abdominal fasciae nearly contiguous 0. similis, Cress. 



PROCEEDINGS EXT. SOC. IHIILAD. FEBRUARY, 1867. 



