EXTERNAL ANATOMY OF INSECTS. 607 



ral, these parts are separate and may be more distinctly 

 traced, the axis of the Costal Area being generally the 

 longest, and that of the Intermediate often the shortest; 

 these axes are suspended in the wing-socket by elas- 

 tic ligaments, intermixed with hard bony plates, the 

 principal one of which, called by M. Chabrier the hu- 

 merus a , is connected both with the tegmen and the 

 trunk, and in some a little resembles the head and neck 

 of a swan. This structure permits the animal to move 

 the lateral areas in some degree separately, so that each, 

 especially the anal, shall form an angle with the inter- 

 mediate ; as the motion of the latter is not wanted, its 

 axis often falls short of the base, or is obsolete, as in 

 Blatta. 



3. Composition. The three areas, traces of which we 

 had discovered in elytra, are particularly visible in teg- 

 mina. If you take any cockroach [Blatta), you will at 

 first sight see that in it they are divided into three larger 

 portions by stronger nervures or folds ; and if you also 

 take a Mantis, or Locusta Leach, a Fulgora or Tettigo- 

 nia, the same circumstance will strike you, only you will 

 see that in these the intermediate portion terminates also 

 in an axis ; these are what I call the three areas. The 

 external one or Costal is usually the longest and nar- 

 rowest 5 ; the Intermediate one is commonly triangu- 

 lar, with its inner side curvilinear ; and the interior 

 one, or Anal area, in the Orthoptera is rather oblong ; 

 in Fulgora angular, and in Tettigonia it presents an 

 isosceles triangle ; with its vertex to the apex of the 

 wing d . The first of these may be defined as that por- 



a Sur le Voldeslns. c. ii. 327 — . b Plate X. Fig. 2. b: 



e Ibid. c. d Ibid. d\ 



