356 Anvals Entomological Society of America [Vol. XI, 



suture between the epimerum "em2" and episternum "es2" 

 (Fig. 1) is continued downward into the coxal region "cxo" as 

 the coxal suture which divides the coxa into an anterior region 

 (veracoxa) and a posterior region (meron) in higher insects. The 

 mesothoracic coxae are' broader than long, and tend to assume a 

 ring-like outline. 



The Mesosterniim. 



The mesosternum is connected with the pleural region by a 

 pre-coxal bridge "IS2" (Figs. 1 and 2) extending in front of the 

 coxa on either side of the sternum. In the crickets and katy- 

 dids, this region ("Is") forms a distinct plate, the later osternite, 

 but in the grasshoppers, it is fused with the episternal region, 

 although a faint line marks it off from the sternal region ven- 

 trally. This region originates as a lateral wing of the sternal 

 region, although its true nature is sometimes masked by its 

 secondary union with the pleural region. 



A ventral extension of the prepectus "pr2" (Fig. 1) is con- 

 tinued around into the sternal region (Fig. 2, "pr2") and up 

 the surface of the other flank, thus making an anterior marginal 

 sclerite bordering the pleural and sternal regions. The large 

 sternal sclerite immediately behind it is the basisternite "bs2," 

 and posterior to this is the narrow transverse region containing 

 the furcal and spinal pits ("f2" and "SS2") which mark the 

 location of the internal f urea and spina, or processes for muscle 

 attachment. This region corresponds to the united third and 

 fourth principal sternal subdivisions (the furca- and spinaster- 

 nite) to which the designation '' sternellum'' is sometimes 

 applied in the prothoracic region. 



In the posterior region of the mesosternum, a suture extend- 

 ing backward in a broad sweep from each of the furcal pits "f2" 

 marks off a lobe "I2" and "I2" on either side of the sternal region. 

 These two lobes are referred to as the mesosternal lobes by 

 systematists, while the similar lobes "I3" and "I3" marked off 

 in the metasternal region are termed the metasternal lobes, and 

 the relative width between these mesosternal lobes (measured 

 transversely between the points labeled "x" and "x" in the 

 mesothorax) as compared with the distance between the meta- 

 sternal lobes (measured transversely between the points labeled 

 "x" and "x" in the metathorax) is a feature used in classifica- 

 tion. Thus in the grasshopper shown in Fig. 2, the mesosternal 



