1864.] 261 



third segment; basal segment slightly dilated at tip; beneath, black. 

 Length 2i lines; expanse of wings 4 lines. 

 Hdh. — Pennsylvania. E. T. Cresson. 



Section 2. 



8. Mesoleptus obscurus. n. sp. 



Black : mouth and tegulse yellowish : wings hyaline, areolet minute, petio- 

 lated ; legs rufous, the trochanters yellowish ; abdomen with the tip and sides 

 of the 3rd and 4th segments obscure rufous. 



Female. — Black, slightly pubescent, most of mandibles and the 

 palpi, pale yellowish ; antennae two-thirds the length of the body, black, 

 the basal joint beneath dull yellowish ; tegulaj pale yellowish ; meta- 

 thorax with the elevated lines tolerably distinct, the central area i-ather 

 large and subquadrate. Wings hyaline, iridescent, nervures fuscous, 

 pale testaceous at base, costji and stigma pale testaceous, areolet minute, 

 petiolated. Legs rufous, coxae black, the two anterior pairs rufous be- 

 neath, their trochanters yellowish, the posterior tibiae and tarsi slightly 

 obfuscated. Abdomen elongate, slender at base, rather broad and sub- 

 compressed at tip ; first segment slightly dilated towards the tip where 

 it narrows again to the base of the 2nd segment ; apical margins and 

 sides of 3rd and 4th segments obscurely rufous; ventral segments yel- 

 lowish ; ovipositor exserted about one line. Length 3A lines ; expanse 

 of wings 5^ lines. 



Hah. — Illinois. Dr. Samuel Lewis. 



9. Mesoleptus argentifrons, n. sp. 



Black ; face densely clothed with silvery pubescence : mandibles, palpi. 4 

 anterior coxfe and trochanters, pale yellowish ; legs and a band on the 2nd and 

 following abdominal segments rufous : wings hyaline, areolet minute, subtri- 

 angular, petiolated. 



Male. — Black, clothed with a thin silvery pubescence, very dense on 

 the face ; mandibles and palpi pale yellowish ; antennje as long as the 

 body, black, the basal joint piceous ; tegulse yellow; the elevated lines 

 of the metathorax tolerably well defined, the central area rather large, 

 subtriangular. Wings hyaline, nervures and stigma black, areolet 

 mipute, subtriangular, petiolated. Legs pale rufous, the four anterior 

 pair tinged with yellowish ; the four anterior coxfe and trochanters 

 beneath, yellowish ; posterior coxae, their trochanters at base and all 

 the tarsi more or less blackish, the posterior tibife sometimes tinged 

 with yellow. Abdomen long, slender, subcyHndric, rufous; the first, 



