CHARLES W. METZ. 



97 



plates, connected by membranes. They are somewhat bow- 

 shaped and flattened, with the narrow side up. Owing to 

 their delicate structure and the ease with which they are dis- 

 torted, they cannot be depended upon for specific characters. 

 A side view of one of the sagittce is shown in figure 5. The 

 volsellcE (V) are stout, vice-like structures, each with two jaw- 

 like lobes ; they seldom vary noticeably in the genus, so are 

 of little importance in classification. The seventh ventral 

 t>late (fig. 8) consists of two arm-like projections, ^h^ proxi- 



FlG. 10. — Thorax of Prosopis. N,. Pronotum ; w, Posterior lobe of Pronotum showing 

 location of tubercle ; Sets, Mesoscutum ; Tg Tegula ; Plj. Mesopleurum ; Epsj, Mesoepis- 

 ternum ; S2, Mesosternum ; ScU, Mesoscutelluin ; N,, Metanotum ; PI3. Metapleurum ; 

 pU. subdivision of Metapleurum ; IT, Propodeum ; End, Enclosure of Propodeuni ; II, 

 Second abdominal terguni ; Cx, Coxa. 



mal arms (PA) for attachment, uniting at their apices, where 

 are fastened the two broad, thin wings (W). The wings 

 differ greatly between species, and furnish some of the most 

 valuable diagnostic characters. Each is composed of the 

 wing proper, to which may be attached a ^nembranous flap 

 (MF); and which may be modified at base into some sort of 

 a lobe (BL). The eighth ventral plate (fig. 9) is usually 

 quite simple, being composed of a body (B) with four pro- 

 jections. The lateral projections are for attachment to the 

 seventh ventral plate, and do not vary appreciably. The 



TRANS. AM. ENT. SOC, XXXVII. 



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