1865.] 



20 



Abdomen elongate, subfusiform, slender at base, shining; basal seg- 

 ment white with a broad, median, black band; remaining segments 

 black, their apical half white ; ovipositor black, exserted half the length 

 of the abdomen. Length 4$ lines; expanse of wings 8 lines. 

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



Mesostenus tricolor. Brulle. 



Mesostenus tricolor, Brulle. Hym. p. 209. 

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



This species has the metathorax whitish, with its base broadly black, 

 as well as a central and two lateral longitudinal lines, the central one 

 is dilated in the middle and carinated; on the anterior third there is a 

 transverse carina, and on the disk in front of this carina there are two 

 short longitudinal carinse which are approximate until near the base, 

 where they diverge towards the scutellum ; instead of a spine on each 

 siHe posteriorly, there is a transverse, semicircular, acute carina ; the 

 surface is irregularly striated ; the second abdominal segment is whitish 

 on each side at base ; the legs are entirely fulvous, except the tips of 

 the tarsi, which are blackish. The single specimen before me is 4| 

 lines long ; expanse of wings 7 lines. 



Mesostenus subtenuis, n. sp. 



Black; face, orbits, broad annulus on antennse, two lines on mesothorax, most 

 of pleura and metathorax, and bands on abdomen, white ; legs pale fulvous ; 

 wings hyaline; metatborax and basal segment of abdomen spinose. 



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

 and spot on mandibles, white; palpi yellowish; antennae slender, rather 

 longer than the body, black, with a very broad white annulus near the 

 tip. Thorax black, shining, slightly pubescent; mesothorax with two. 

 abbreviated, longitudinal, white lines on the disk, the dorsal lines deeply 

 impressed ; the collar, tegulae, a sutural line before and a spot beneath 

 the anterior wing, a spot beneath and a large space behind the posterior 

 wing, the pleura, scutellum, and the carinae in front and on each side, 

 and the postscutellum, all whitish ; the suture between the pectus and 

 pleura, black; metathorax pubescent, polished, armed with a stout 

 subobtuse spine on each side posteriorly, base black, with a broad cen- 

 tral lonsntudinal black line and a narrow one on each side also black, 

 rest of the surface yellowish, deeper on the sides. Wings hyaline, 

 slightly iridescent; nervures and stigma pale fuscous; areolet much 

 larger than usual. Legs long and slender, p-de fulvous; the tarsi, espe- 

 cially the posterior pair, whitish, dusky at extreme tips. Abdomen 

 elongate, subcompressed, shining, slender at base; first segment dilated 

 on each side about the middle into a large, stout tubercle; remaining 



