30 [January 



segments clothed especially on the sides with short, blackish pube- 

 scence ; basal segment white, with a central blackish stripe ; second 

 segment also white, with a broad central black band not touching the 

 lateral margins, and a black line on each side at base confluent with the 

 basal margin which is also black ; remaining segments white, more or 

 less black at base, but this color not touching the lateral margins. 

 Length 3| lilies; expanse of wings 6J lines. 



Collection. — Ent. Soc. Philad. One specimen. 



Easily recognized by the large tubercle on each side of the basal 

 segment of the abdomen. 



-'.-■ 



Mesostenus semialbus, n. sp. 



Black; face, orbits, annulus on antennae, two lines on mesothorax, most of 

 pleura, metathorax and abdomen, white; legs fulvous; wings hyaline; meta- 

 thorax with two long acute spines. 



Female. — Head black ; face, orbits, broad on the cheeks, clypeus. 

 spot on mandibles, and palpi, white; antennae about as long as the body, 

 slender, black, with a broad white annulus a little beyond the middle, 

 basal joint beneath with a pale spot. Thorax : mesothorax black, with 

 two short lines on the disk, the dorsal lines deeply impressed ; pectus 

 black, aciculate, its upper margin bordering on the mesothorax, and a 

 spot over each anterior coxa, white; tegulae, a spot beneath the anterior 

 wings and the pleura, sides and beneath except the lateral sutures, 

 whitish ; scutellum black, with a large white spot at tip, the carina on 

 each side in front, the postscutellum, as well as the lateral carina? lead- 

 ing to the base of the wings, also whitish ; metathorax elongate, slightly 

 pubescent, armed posteriorly with two long acute spines, whitish, a 

 broad, central longitudinal stripe, broadly dilated at base, a narrow 

 stripe on each side just outside of the spines, commencing in a spot 

 near the base, and a small spot on each extreme side posteriorly, black ; 

 the dorsal surface just above the spines, and the sides are aciculate. 

 Wings hyaline, slightly dusky at tips ; nervures and stigma fuscous ; 

 areolet larger than usual. Legs long and slender, pale fulvous, the 

 tarsi dusky at tips; coxae whitish, each with an exterior black longitu- 

 dinal line. Abdomen elongate, subfusiform. slender at base and sub- 

 compressed at tip, shining; basal segment black, with the tip and lateral 

 margins white ; second segment white, with a large triangular mark 

 near the tip, and a short line on each side at base, confluent with the 

 basal margin, black; third segment white, with its basal margin and a 

 broad transverse mark confluent with the base, black ; remaining seg- 

 ments white, with their basal margins narrowly black ; ovipositor 



