1864.] 



263 



the four anterior trochanters beneath yellowish, the posterior tarsi ob- 

 fuscated, pale at base. Abdomen black, the apical half of the 2nd, the 

 3rd except its base and the 4th segment entirely, rufous, sometimes the 

 base of the 5th segment is also rufous ; apex rather broad and com- 

 pressed ; beneath, more or less tinged with yellowish ; ovipositor exser- 

 ted about half a line. Length 21-3 lines ; expanse of wings 4-41 lines. 



Male. — Resembles the female, except that the antennae are longer, 

 with its basal joint sometimes entirely dull rufous, and the apex of the 

 abdomen subcylindric, scarcely compressed. Length 3 lines. 



Hah. — Delaware (Dr. T. B. Wilson) ; Illinois (Dr. Samuel Lewis). 



This seems to be the most common species. 



12. Mesoleptus affinis, n. sp. 



Black; si^ot on mandibles, palpi, tegulae and base of four anterior legs, yel- 

 low; wings hyaline, areolet minute oblique, petiolated; legs and the apical 

 two-thirds of abdomen, rufous. 



Male. — Black, the head and thorax with a slight silvery pubescence ; 

 a spot on each mandible, and the palpi, pale yellowish ; antennae as long 

 as the body, black, the basal joint dull rufous. Thorax black, the teg- 

 ulse pale yellowish, metathorax with the elevated lines indistinct, the 

 central area very elongate, not well defined. Wings hyaline, iridescent; 

 nervures and stigma black ; areolet minvite, oblique, peliolated. Legs 

 pale rufous, the anterior coxte and all the trochanters, yellowish, the 

 posterior tarsi obfuscated, pale at base. Abdomen obscure rufous, the 

 first segment except extreme tip, basal half of the second, and extreme 

 base of the third, black; middle of the apical segments obfuscated; 

 apex broad, compressed, appendages blackish. Length 2| lines; ex- 

 panse of wings 4i lines. 



Hah. — Illinois. Dr. Samuel Lewis. 



Very closely allied to M. Oxylus., but differs by the minute oblique 

 areolet of the wings, by the anterior coxse and all the trochanters being 

 yellow, and by the apical segments of the abdomen being broadly com- 

 pressed and entirely rufous. 



13. Mesoleptus flavirictus, n. sp. 



Black ; face silvery : m andibles, palpi, basal joint of antennae beneath, tegulse 

 and the legs at base, yellow ; rest of legs and the abdomen except base and 

 apex, rufous ; wings hyaline, areolet small, oblique. 



Female. — Black, thinly clothed with silvery pubescence, more obvi- 



