1918] Thoracic Sclerites of Dissosteira 357 



lobes are only "slightly more distant than the metasternal 

 lobes"; in other words, the distance from "x" to "x" in the 

 mesosternum is subequal to that from "x" to "x" in the meta- 

 sternum. In the males, however, the mesosternal lobes may be 

 nearly twice as distant as the metasternal lobes, so that this 

 feature holds good only for females. 



METATHORAX. 



In the crickets, mole-crickets and most katydids, the 

 metathorax is markedly larger than the mesothorax, especially 

 in the tergal region (as is also true of a few other insects, such 

 as the earwigs, beetles, Strepsiptera, etc.) and one would 

 naturally expect the same to be true of the grasshopper group 

 also, since the hind wings and hind legs are much larger than 

 the others and consequently require larger muscles for operating 

 them. The meso- and metathorax are subequal in size, how- 

 ever, in Dissosteira, and the two wing-bearing segments are 

 more or less closely united to furnish a firmer support for the 

 wing muscles, since the grasshoppers are better fliers than the 

 crickets and katydids. 



The Metanotiim. 

 An anterior region "pscs" which corresponds to the prescu-_ 

 turn is indistinctly marked off in the tergal region of the meta- 

 thorax (Fig. 3), and behind it is the scutum "^Ca" which is of 

 a somewhat indefinite extent. The parascutellar regions "jss" 

 of the metanotum are not strictly homologous with the regions 

 labeled "js." in the mesonotum, since they extend over a 

 greater area in the metanotum ; but it is inadvisable to attempt 

 to distinguish between the two in the different segments, since 

 they are practically the same in position, etc., in both meso- 

 and metathorax. The metathoracic sciUellum "sla" is not very 

 different from the mesothoracic scutellum "slo"; but the 

 poster gite "pOs" or region behind the scutellum is of greatei 

 extent in the metathorax than in the mesothorax ("po"). 

 The mesothoracic postscutellum is greatly reduced, and is 

 overlapped by the region "po," but in the metathorax, the 

 postscutellum "psU" is large and well. developed, although it is 

 more or less closely united with the first abdominal tergum. 

 Along its posterior margin, it bears an internal transverse ridg.e 

 or phragma, to which certain longitudinal dorsal muscles are 



