ORTllOPTERA OF INDIANA. 



135 



a squarish tongnc or forward prolongation of the metasternum. The 

 latter is iniited with tlie basal abdominal segment by the dovetailing 

 of a similar but narrower tongue between its lobes. The side pieces 

 of the mesothorax and metathorax are called "pleurites"' and bear 

 the prefixes "meso" and "meta." 



The Wings. — These are thin, broad, more or less leaf-like folds 

 of the integument or body covering, which are joined to the thorax 

 and moved by powerful muscles located within the thoracic cavity. 

 The first or outer pair of wings of the locust and other Orthoptera 

 serve as shields or covers for the more delicate inner pair. In the 

 text which follows they are called "wing covers" or "tegmina." Each 

 wing cover is a thin, more or less transparent, leathery or parchment- 

 like plate of cliitin; strengthened by a network of tubes called 

 "nerves" or "veins." The spaces enclosed by the veins and their 

 cross branches are calk'd "fells."' When folded and at rest upon the 

 body the outer faces of the tegmina of a locust are vertical, with the 

 front or costal margin below, and the posterior or sutural margin 

 lying along the back; that of the left wing cover slightly overlapping 

 the right. 



The principal veins of the tegmina of a locust diverge from the 

 basal end and are seven in number. The one nearest the front or 

 lower margin of the wiuij cover is the "sub-marffinal" or "costal 



Fig. 9. Right tegmina of a locust, showing the venation. The names of the veins desig- 

 nated by the letters are given in the text. 

 (After Saussure.) 



vein" (c). It is undivided, and may usually be traced for a little 

 more than half the length of the tegmina, though in some locusts it 

 is lacking. The second and longer vein, also undivided, is the 

 "mediastinal" (m). The third and much larger vein is the "humer- 

 al" (It), sometimes called the "sub-costal." It gives rise to several 

 large branches, the sub-divisions of which form the framework of 

 the greater part of the wing cover. The larger of these branches 



