384 ERNEST A. BACK. 



of two or three each; the seventh and eighth segments very 

 obscure, retracted within the sixth segment and, together with 

 the small hypopygium, not visible from above. Head very 

 much broader than high, face and front broad, of nearly equal 

 width, the front not widening above, the face only gently con- 

 vex, and but with little protuberance below. Oral margin 

 clothed with not dense bristly hair, the face above with fine 

 sparse pile reaching nearly to the antennas. Antennae (PI. IV, 

 fig. 4) rather short; first two segments very short, the first 

 always a trifle longer than the second, the third usually slender, 

 about twice as long as the basal segments, and bearing a 

 terminal more or less bristle-like style which is of variable 

 length. Vertex moderately depressed, ocellar tubercle large. 

 Thoracic dorsum strongly arched; the scutellum much as in 

 Dioctria. Thoracic dorsum clothed in all the species with 

 sparse, inconspicuous hair on the middle, on the lateral and 

 posterior portions with weak bristles. Scutellum with two 

 very weak, almost hair-like bristles, on the posterior margin, 

 and above clothed with fine silky pile directed backward. 

 Abdomen in both male and female much depressed; in the 

 female more convex, and the eight segments appear normal, 

 the last bearing the ovipositor with its terminal circlet of 

 spines; in the male as above described, the fifth and sixth 

 segments are always very broad and flat, the fifth being sub- 

 ject to some variation in proportion between its width and 

 length. Hind tibiae thickened at tip, and the hind tarsi con- 

 siderably stouter than the anterior pairs; pulvilli normal. 

 Wings rather long, more or less marked and spotted with brown 

 or black; all the posterior and submarginal cells wide open, 

 the anal cell only slightly so. 



Type. — Pygotolus argentifer Loew, now a synonym of Dasy- 

 pogon politus Say. 



I regret that I have had so little material of this genus with 

 with which to work and make descriptions. 



