18 PROC. ENT. SOC. WASH., VOL. 24, NO. 1, JAN., 1922 



part of the tergum of the prothorax and the pleura, which are 

 indistinguishably fused together. Anteriorly the outline of this 

 area is subogival (more or less resembling a pointed arch); 

 for a short distance along the middle its sides are nearly parallel; 

 its posterior margin is oblique and widely sinuate and bears 

 the vague suture described above. This pronotal-epipleural 

 area is nearly flat except for a shallow excavation near the 

 posterior angle. 



The coxae of the prothorax are subglobular and prominent. 



MESOTHORAX. Little of the notum of the mesothorax is 

 visible without removing the elytra, except the prominent 

 elevation of the scutellum (scl, fig. 14) which rises between 

 the bases of the elytra to approximately the plane of their 

 disc. In communis Gyll., the prescutum (psc, fig. 14) is roughly 

 yoke-shaped, transverse and has a medianly reentrant anterior 

 margin and a strongly depressed central area. It bears the 

 anterior notal wing process (ANP, fig. 14). The elevated 

 portion of the scutellum is suboval and prominent, sloping 

 away sharply on either side to the axillary cord (AxC2, fig. 14). 

 The scutum (set, fig. 14) is small and closely fused with the 

 scutellum; it bears the posterior notal wing process (PNP, fig. 

 14). The structure of the notum of the mesothorax is generally 

 uniform in all the species so far examined. 



The sternum of the mesothorax (St 2, fig. 17) \nfissilis Say is 

 roughly pelecoidal (i. e., like the axe of the Roman fascis), 

 and except for its posterior intercoxal portion is not so promi- 

 nent ventrally as the sternum of themetathorax. The anterior 

 margin is double, being split transversely; each of these anterior 

 edges is interrupted by a prominent median bifid knob which 

 marks the anterior end of the mesosternal cavity. The lateral 

 margins of the sternum slope away to meet the coxal cavities. 

 The posterior margin of the sternum is defined by the regularly 

 rounded coxal cavities which are separated by a space equal to 

 about one-third the width of the anterior margin of the sternum. 

 The posterior part of the sclerite ends at the narrowest point 

 between the coxae, and the margin is marked by the transverse, 

 deeply incised meso-metasternal suture. The mesosternal 

 cavity (MsC, figs. 17 & 18), which occupies about one-third 

 the entire area of the sclerite, is roughly oval; its posterior 

 margin is met by the concave, declivous intercoxal portion of 

 the mesosternum. 



The episternum of the mesothorax (eps2, fig. 18) in fissilis 

 Say, is roughly triangular, with its exterior angle bluntly 

 rounded; its anterior margin is sinuate and oblique; its interior 

 margin is concave. Its exterior margin is convex and on its 

 anterior part has an oblique marginal cleft just below the exterior 

 angle, into which the inflexed margin of the elytron fits when 

 at rest. 



