606 EXTERNAL ANATOMY OF INSECTS. 
one, or Anal area, in the Orthoptera is rather oblong ; 
in Fulgora angular, and in Cicada it presents an isos- 
celes triangle; with its vertex to the apex of the wing?. 
The first of these may be defined as that portion of the 
tegmen that lies betweeen the costal and postcostal 
nervures; and perhaps, in some cases, as in Mantis, for 
there is the fold, the mediastinal may be regarded as its 
limit; the Intermediate Area is that which lies between 
the postcostal or mediastinal nervure and the anal fold 
of the tegmen; and the Anal Area is the remainder. 
These areas may perhaps best be made out by tracing 
each to its axis. To study them carefully in tegmina 
and hemelytra is of considerable importance; for in them 
we find the first outline of the general plan upon which 
the wings of insects are constructed, and which, as we 
shall see hereafter, more or less enters into the compo- 
sition of them all. 
4. Position, and folding in repose. With regard to 
their position when not expanded, ¢egmina vary some- 
what in the different tribes. In the Coleoptera we have 
seen that, except in a few instances, the elytra unite at 
their suture. Something like this takes place in Ful- 
gora, Cercopis and affinities, in the Homopterous Hemz- 
ptera ; in these though the union is not near so exact, 
yet the zegmina do not lap over each other; they are 
usually more or less deflexed, with scarcely any portion 
in a horizontal position: in Cicada, Chermes, Aphis, &c., 
the middle part only of these organs meets, from which 
point they diverge both towards their base and apex?. 
In the Orthopiera the position is quite different, for one 
@ PrateE X, Fie, 2, d:. ® Stoll Cigales, t. viii. f. 39. 
