162 PROCEEDINGS OF THE ACADEMY OP 



one very prominent on each side ; al)donien polished, slender at 

 base and then oblong-ovate; areolet very minute, open; antennas 

 long and very slender. Length 3^ lines. 

 Orizaba. 



24. Mesostenus pertenuis, n. sp. 



%. Hone3'-3'ellow ; head, antenna, pro- and mesothorax, scu- 

 tellar region and anterior portion of pleura beneath, black ; lace, 

 mouth, orbits, annuhis on antenn.ie, collar, teguhB, line before, spot 

 beneath confluent with anterior margin of pleura, spot on disk of 

 raesothorax, apex and sides of scutellura, two oblique lines in front, 

 spot on postscutellum, pleura beneath, four anterior coxse and 

 trochanters, and posterior tarsi except base and apex, white; wings 

 hyaline, iridescent, apex faintly dusky ; tips of posterior tibiie 

 dusky, base and apex of their tarsi black. Slender, shining, feebly 

 punctured ; metathorax rounded, without tubercles ; abdomen 

 long, very slender throughout ; areolet very minute, closed. Length 

 4^ lines. 



Cordova. 



25. Mesostenus collaris, n sp. 



Z. Honey -yellow; head, antennae, prothorax, sutures of meso- 

 thorax, spot behind anterior coxae, and space on each side of scu- 

 tellum, black; face, mouth, orbits, annulus on antenna?, margins 

 of prothorax, tegulae, spot beneath, two dots in front of scutellum, 

 spot on postscutellum, metathoracic tubercles, four anterior coxae 

 and trochanters, and second, third and fourth joints of posterior 

 tarsi, white; wings h3^aline, iridescent; posterior tibife dusky 

 toward tips, basal and apical joints of their tarsi fuscous. Small, 

 slender, opaque; metathorax coarsely reticulated, tubercles short, 

 robust and obtuse; areolet minute, open. Length 3 lines. 



Orizaba. 



26. Mesostenus arctus, n. sp. 



%. Black; clj'peus, spot on mandibles, palpi, four anterior 

 coxae and trochanters and posterior tarsi except base and apex, 

 white; four anterior legs pale honey-yellow; wings hyaline, iri- 

 descent, duvky at tips. Small and very slender, especially the 

 antennae, legs, and base of abdomen ; mesothorax densely and 

 coursel\' granulated ; metathorax coarsely reticulated, witliout 

 prominent tubercles; areolet quadrate, closed; first abdominal 

 segment narrow, of uniform width, with a prominent tubercle on 



