1899.] NATURAL SCIENCES OF PHILADELPHIA. 413 



strong; remainiDg segments very finely punctured; second sub- 

 marginal cell with a radial side about equal to half the distance 

 between the recurrent veins on the cubital vein; third subniar- 

 ginal rhomboidal, the outer nervure nearly straight. Length 

 15 mm. 



Chapada, April. One specimen. The coloration of wings is 

 similar to Z. fraternus. The short flagelhim and wide laterally 

 angulate clypeus, cristate pronotum, and markings, distinguish Z. 

 crmatus. 



aa. Postscutellum carinated, dentate, or emarginate. 



Zethus imperfectus n. sp. 



Black, with thin silky pile, most evident on thorax on sides and 

 beneath and second segment; lateral margins of clypeus, hne on 

 inner margin of mandibles, spot in each eye emargination and at 

 bases of antennae spot on cheeks above, line on pronotum anteri- 

 orly, dot on tegulse at base and apex, line on postscutellum, stripe 

 on fore femora behind, and on all the tibise, and apical margins 

 of all segments, including the sixth dorsal, yellow, that at apex 

 of petiole continued a short distance along sides ; flagellum beneath 

 reddish yellow, except basally; wings subhyaline, slightly brown- 

 ish in costal cell. 



? . — Head with deep separated punctures, sparse on cheeks ; 

 clypeus rounded at sides, its length equal to considerably more than 

 half its width, closely and finely punctured and in addition with 

 some larger, shallow, sparse punctures, its fore margin subemargi- 

 nate, indistinctly dentate at each side; an indistinct T-shaped 

 carina between antennal bases; flagellum short, clavate, the scape 

 slender, cylindrical, scarcely dilated apicaliy, in length not quite 

 equal to pedicel and following four joints united; space between 

 hind ocelli equal to nearly two-thirds of that between them and 

 eyes ; pronotum cristate, not dentate, Avith very coarse punctures ; 

 dorsulum with the punctures more separated, anteriorly with a shal- 

 low impressed line medially, the usual posterior impressed lines or 

 furrows, entirely wanting ; scutellum scarcely impressed, with 

 shallower punctures; postscutellum very indistinctly dentate later- 

 ally; middle segment concave, medially sulcate, the concavity 

 smooth, that portion between the concavity and sides, rugose, 

 bounded externally by a carina, sides finely punctured, subcari- 



