Fossorial Bymenoptera of North America. 419 



as the coxae, being slender. Hind coxa; nearly twice as long as broad, 

 the costal sub-triangular; femora slender, swelled, often cultrate in 

 shape, fore tarsi long and slender; those of the 9 broader, and the 

 middle joints sub-triangular; hind tibia) trigonate, nearly smooth, 

 spurs long and curved; hind tarsi long and slender, lobes only spined ; 

 much shorter and stouter in 9 than in % . 



Primaries with the 2d costal vein long, triangular ; the upper side 

 of the 1st sub-costal space is regularly curved, not so angulated as 

 usual; 2d space pentagonal, the inner side bent in the middle, and 

 sending a short vein back into the 1st space; the 3d is nearly square, 

 oblique. The 1st median space is produced rhomboidal, the outer 

 angle being rounded ; 2d space 5-sided, very irregular, the inner half 

 being half as broad as the outer side ; 2d internal one-third as broad 

 as long. The secondaries have the median nervure much bent in- 

 wards after leaving its branch in the middle of the wing. The interno- 

 median recurrent is very oblique, joining the median beyond the origin 

 of the median ncrvule, so that it is much nearer the margin than in 

 any other genus of the group. The wing is broad and rather deeply 

 lobed at the base. Abdomen long, a little longer than head and thorax, 

 ovate or sub-clavate, flattened, pedunculated, the outer half of the 1st 

 joint widens towards the end, much as in Eumenes. In the 9 the 

 abdomen is shorter, more ovate than in % . 



The genus is easily known by its flat front, indented eyes, very short 

 clypeus, slender antennas; by the abdomen tapering behind more rapidly 

 than usual, the horizontal middle flank being overlaid by the hind flanks; 

 also by the very distinct large enclosure of the propodeum, with its 

 plain suture; this piece, which is seen less distinctly in Oxybelus, is 

 here very apparent ; the pedunculated abdomen varies sexually and 

 specifically in its length and proportions. Indeed there is a good deal 

 of variation in the species as regards the front of the head, which 

 narrows behind more in the 9 than % . Tbe tip of the abdomen is 

 plain, not. ridged, and the styles do not appear in the % . The females 

 appear to possess no sting. 



Mellinus bimaculatus, Say, MS. 



M. bimaculatus, Harr., Cat. Ins., Mass., p. 68. (18.35). 

 9 . Head dull black, densely but minutely punctured, orbits striped 

 with yellow on each side; mandibles smooth, piceous, upper edge nar- 

 rowly yellowish; antennae dark, terminal half testaceous on the sides; 

 the three terminal joints broadly annulated with testaceous. Protho- 

 rax yellow above, thorax black, very minutely punctured, somewhat 



