14 BULLETIN 03, UNITED STATES NATIONAL MUSEUM. 



margin truncate, feebl}^ arcuate or sinuate even in individuals of the 

 same species, widel}^ sej^arating the mesocoxa? and terminating at 

 Ihe transverse mid-acetabuLTr line; each lateral third of the posterior 

 border of the mesosternum is arcuately reentrant, forming the anterior 

 moiety of each mesacetabular cavity, and terminating in the exteruo- 

 posterior augle, which is rather broad and transversely truncate, 

 forming the anterior boundary of the inesacctahular recess (see Ace- 

 tabula) ; the surface is more or less concave at middle between the 

 convex and prominent acetabular margins. 



The sides of the mesosternum are limited by the mesosternal sutures ; 

 these are straight and extend obliquely forAvard and inward from 

 the external angle of the mesacetabular recess, to the condylar mar- 

 gin, at a point whose distance from the mid-line is about equal to the 

 length of the condylar portion in the mid-line before the prominent 

 intercoxal part. The sutures join the mesosternum and episterna 

 only. 



Mesosternal episterna. — Each episternum is triangular and with its 

 surface on the same general plane; anteriorly forming the condylar 

 margin between that formed by the mesosternum below and the meso- 

 notum above ; internally uniting with the mesosternum ; apical angle 

 received between the epimeron and mesosternum at the angle of the 

 mesacetabular recess; externally and dorsally connate with the epi- 

 pleural margin and base of the elytron external to its articular process. 



Th(> sm-face is divided into two areas by a gentle arcuate line or 

 ridge which extends transversely from about the middle of the meso- 

 sternal suture to the inferior humeral angle. This line may be called 

 the epistemal line. 



The area anterior to the episternal line is the condylar portion; its 

 surface is finely punctulo-scabrous and pubescent, and subdivided 

 into two unequal portions by a subma^'ginal line, which, beginning at 

 the antero-internal angle runs outward nearly parallel to the mar- 

 ginal bead, thence gentlv diverging, to arcuately pass to the middle 

 of the superior margin of the condylar area. 



Mesosternal epimera.—F^^ch epimeron is rhomboidal, with its in- 

 ferior border bounding the mesacetabular recess externally ; scarcely 

 twice as wide as long, obliquely placed between the mesosternal epi- 

 sternum in front and the metasternal episternum behind, and if its 

 l)osterior nuirgin be prolonged as a line it will touch the internal angle 

 of the metacoxa of the same side. 



The superior margins of the mesosternal episterna and epimera are 

 indexed beneath the inferior epipleural margins of the elytra, at the 

 line of inflexion where they pass under, the surface is grooved and 

 beveled to receive and hold the elytral margins; the inflexed portions 

 are continuous with less strongly chitinized dorsal and undifferen- 

 tiated sclerites, which with similarly inflexed parts of the metasternal 



