18 



ORTHOPTERA OF NORTHEASTERN AMERICA. 



basal abdominal segment by the dove-tailing of a similar but nar- 

 rower tongue between its lobes. The side pieces of the mesotho- 

 rax and metathorax are called pic u rites and bear the prefixes 

 iitcxo and ineta. 



The ii'lnys 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 Orthop- 

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

 In the text which follows they are called tegmina. Each wing 

 cover or tegmen is a thin, more or less transparent, leathery or 

 parchment-like plate of chitin, strengthened by a network of tubes 

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

 cross branches are called cells. When folded and at rest upon 

 the body the outer face of the tegmen of a locust is vertical, with 

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

 margin lying along the back; that of the left tegmen slightly over- 

 lapping the right. 



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

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

 lower margin of the tegmen is the suftmarginal or costal vein (c). 



d h d' d 



Fig. 8. Right tegmen of a locust, showing the venation. The names of the veins desig- 

 nated by the letters are given in the text. (After Saussure.) 



It is undivided, and may usually be traced for a little more than 

 half the length of the tegmen, though in some locusts it is lacking. 

 The second and longer vein, also undivided, is the media si i mil 

 (HI). The third and much larger vein is the Jut literal ( // ) , some- 

 times called the subcostal. It gives rise to several large branches, 

 the subdivisions of which form the framework of the greater part 

 of the tegmen. The larger of these branches (Y7), is known as the 

 dixcoidal vein, its branches being designated as d', dd", etc. The 

 fourth or median vein (u), is much smaller and soon divides into 



