NATURAL SCIENCES OF PniLADELPHTA. 153 



3. Mesostenns compactus, n. sp. 



9. Black; face, clypeus, spot on mandibles, orbits in-egular 

 in front and dilated on cheeks, annnlus on antennte, collar, tegnlae, 

 spot in front, another beneath, another on disk of mesothorax, 

 apex of scutellum, two spots in front, postscntelhim, two slender 

 lines to base of wings, space behind, wings, pleura beneath, spot 

 on each side, two broad stripes on posterior face of metathorax 

 covering spines, and a large mark on flanks, white or whitish ; 

 wings hyaline, nervures black; legs luteous yellow, coxae whitish, 

 spot on posterior coxae, base and apex of trochanters, four ante- 

 rior femora above, stripe on upper and lower edge of posterior 

 pair, confluent at base and apex within, black ; abdomen black 

 above, base of first segment, broad apical margin of all the seg- 

 ments and three spots at base of second the central one trans- 

 verse, the lateral ones sublunate j^ellowish-white, the two apical 

 segments have a central black band. Robust, compact, opaque ; 

 mesothorax densely and coarsely' pitted ; metathorax rugose, reti- 

 culated ; abdomen smooth and shining, robust, first segment 

 squarel}"^ dilated at tip; upper lateral angles of prothorax pro- 

 duced into a prominent, robust, subacute spine; metathoracic 

 spines prominent and obtuse; areolet small, quadrate, closed. 

 Length 5 lines. 



Orizaba. 



4. Mesostenus discus, n. sp. 



9. Differs from propinquus as follows: Orbits interrupted 

 behind eyes; scutellum very flat, entirely yellowish-white ; with- 

 out spots in front; the posterior coxae have a cordate black spot 

 above, confluent with apical suture, their femora have two black 

 stripes above and one beneath, all confluent at base and apex, tips 

 of all their tarsi black ; the meso- and metathorax are densely 

 and coarsely rugose, the former finely striated on disk ; the areo- 

 let is small, quadrate and open ; the upper lateral angles of pro- 

 thorax are prominent. Length 6-6^ lines. 



Orizaba. 



5. Mesostenus facilis, n. sp. 



9 . Very much like discus, except that the posterior coxa) have 



two short black stripes above, and their femora a black stripe on 



each side above; the tibiie and tarsi are yellow, the latter tipped 



with black, the posterior pair lemon-yellow ; the abdomen is more 



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