368 ERNEST A. BACK. 



% ?. — Length 17-26 mm. — Robust, rich reddish-brown species. 

 Thoracic dorsum with or without faint traces of the usual black stripe; 

 abdomen wholly reddish-brown, the sides of the segments adorned 

 with a black and white pruinose spot; clothing of the palpi, thorax and 

 legs wholly black ; hair and bristles of coxa? rarely wholly, always 

 partly, black; wings tinged with brownish. 



Face, front and occiput densely pale golden pruinose; mystax dense, 

 yellowish-white; the face above clothed with a few scattering incon- 

 spicuous black hairs ; front along orbits and before the ocellar tubercle 

 with black hairs. Antennas reddish-brown; second segment nearly 

 twice as long as the first, both covered with black hair; third segment 

 clothed above on the basal half with black hair more dense than in 

 many of the other species; style black. Palpi brownish with black 

 hair, sometimes intermixed with paler hair; proboscis black, brownish 

 at base below. Ocellar tubercle and upper occiput with black bristles; 

 the occiput below with paler bristles and hair. Thoracic dorsum ob- 

 scurely adorned with three black stripes; the median stripe greatly 

 abbreviated posteriorly (usually before the middle of the dorsum) , 

 geminate, the two parts being separated by a distinct interval; lateral 

 stripes abbreviated anteriorly, strongly bisected at the transverse 

 suture (see note). The short hair and the bristles of the dorsum 

 black; on the pleura? short hair is present on the posterior portion of 

 the mesopleuras and on the upper portion of the sternopleurae; tri- 

 chostical and scutellar bristles black. Abdomen very robust, much 

 stouter than in discolor and platyptera, wholly reddish-brown or red- 

 dish-yellow; above, on the sides of the segments, especially distinct 

 on segments 2-5, are two spots, the anterior one is black and extending 

 from the anterior angle of the segment backward and upward, and 

 ending a trifle beyond the middle of the segment; the second spot is 

 yellowish-white, sometimes quite white, and extends backward to the 

 posterior margin covering the rest of the lateral margin. Venter 

 brownish. Abdomen clothed with very short black hair, the bristles 

 on the sides of the first segment black ; genitalia of male reddish- 

 brown, with longer black hair. Legs blackish-brown, varying to a 

 lighter color, the base of the tarsal segments often paler; all the bristles 

 and hair black; the coxas of the same color as the pleurae, the front 

 pair usually with numerous brownish, as well as black, hairs, the two 

 posterior pairs usually almost wholly with black shorter hair. Claws 

 black, pulvilli yellowish-white. Wings yellowish hyaline, inclined to 

 be slightly variable; the anal cell and posterior angle much clearer 

 and nearly destitute of microscopic pubes. 



Type.—M. C. Z. 



Habitat. — Vt. ; Hanover, N. H.; Amherst (July 20-Aug. 22), 

 and Wareham (July 29, H. J. Franklin), Mass.; Conn.; N. Y. 

 (July); N.J. (July 14); Pa.; 111. 



