1864.] 271 



iridescent ; nervures and stigma blackish, pale at base ; areolet subtri- 

 angular, very slightly peliolated. Legs color of the body, tolerably 

 slender. Abdomen, slender at base and gradually dilated towards the 

 apex, polished ; basal segment dilated at tip, the sides carinated with- 

 out tubercles, and the disk slightly canaliculate ; apical segments thick- 

 ened and sometimes subcompressed. Length Si — 4 lines; expanse of 

 wings 6 — 7 lines. 



Hah. — New Jersey. E. T. Cresson. 



28. Mesoleptus unicolor, n. sp. 



Yellowisjh-testaceous ; wings hyaline, areolet subtriangular, oblique; abdo- 

 men slightly petiolated, clavate. 



Entirely dull yellowish-testaceous or pale honey-yellow, the face, teg- 

 ulfe, pleura and tarsi much paler; antennse very slender and longer 

 than the body ; mesothorax more or less obfuscated on the disk ; meta- 

 thorax with the elevated lines not well defined, the central area narrow 

 and very elongate. Wings ample, hyaline, glossy and beautifully iride- 

 scent ; nervures fuscous, pale at base, stigma large, fuscous, pale at base ; 

 areolet subtriangular, rather oblique, and slightly petiolated, the outer 

 nervure rounded, the 2nd recurrent nervure straight. Legs rather 

 slender, color of the body, the tarsi paler and blackish at tip. Abdomen 

 clavate, slightly petiolated, slender at base and thickened towards the 

 apex, polished; basal segment gradually dilated towards the tip, the 

 sides carinated and without tubercles ; apical segments rather broad, 

 subcompressed, and somewhat obfuscated. Length 3 lines ; expanse of 

 wings 6 lines. 



Hah. — Pennsylvania; Delaware. Dr. Thos. B. Wilson. 



Smaller than M. concolor and somewhat paler in color, otherwise 

 they are much alike. 



29. Mesoleptus discolor, n. sp. 



Pale testaceous ; the vertex, antennae, mesothorax, scutellum, metathorax, 

 sides of pleura, and basal segment of abdomen, blackish ; wings hyaline, areo- 

 let subtriangular, oblique. 



Male. — Pale testaceous, shining; a large spot encircling the ocelli, 

 and the occiput, blackish; autenufe very slender, longer than the body, 

 blackish, pale testaceous at base. Thorax : mesothorax blackish, with 

 two subobsolete, pale, longitudinal lines ou the disk ; tegulfe and pleura 

 pale testaceous, the latter with a large blackish patch on each side; scu- 



