NATURAL SCIENCES OF PHILADELPHIA. 157 



black line clown each side id a subapical black spot, and, instead 

 of there being tAvo round spots at base, there are three, the lateral 

 one transverse, notched behind at the spiracles and confluent 

 with spot on the flanks, the middle one a narrow transverse line 

 bent at right angles posteriorly, the surface smooth with two 

 transverse suliarcuate carinas; the coxre have an elongate black 

 mark on outside, the posterior pair immaculate within ; tips of 

 posterior tarsi black; bands of abdomen white, dilated laterally, 

 base of second segment without spot ; the seventh segment large, 

 as in the two preceding species. Length 5^ lines, 

 Orizaba. 



13. Mesostenus mexicanus, n. sp. 



9. Black; face, mouth, orbits interrupted beliind eyes, white 

 annulus on antennne, collar, tegub^, line before, another beneath, 

 two short discal lines on mesothorax, two oblique lines in front 

 of scutellum, apex of scutellum and postscutellum, large elongate 

 mark on pleura, mark behind wings, two elongate marks on pos- 

 terior face of metathorax covering spines, a large ovate mark on 

 flanks, posterior coxae except outward black stripe, base and apex 

 of first abdominal segment, lateral and broad apical margins of 

 remaining segments, white ; wings h3'aline, apical margins nar- 

 rowly dusky ; legs luteous, tibitB and tarsi yellowish, all the 

 femora black al)ove. Robust ; thorax punctured ; metathorax 

 transversely striated behind, the striae confused or radiating 

 above the spines, extreme base smooth, the spines subacute, 

 prominent; abdomen robust, smooth and shining, first segment 

 squarel}'^ dilated at apex, gastrocoeli indicated by a transverse 

 white spot. Length 7 lines. 



%. More slender, antennsB and legs longer, knees and apex of 

 posterior tibiae black. Length 6 lines. 



Orizaba; Cordova. (Sumichrast, No. t.) 



14. Mesostenus lassatus, n. sp. 



%. Black; face, mouth, orbits, cheeks, scape beneath, collar, 

 tegulae, dilated line before, dot beneath, two short discal lines on 

 mesothorax, scutellums, space behind base of wings, pleura ex- 

 cept anterior margins, flanks of metathorax, tvvo elongate spots 

 on posterior face covering tubercles, coxae, posterior tarsi, base of 

 first abdominal segment and apical margin of all the segments, 

 white ; wings hyaline, iridescent, apical margin faiutly dusky ; 



