EXTERNAL ANATOMY OF INSECTS. 633 
the wing is occupied by the apical areolets *; though in 
some cases they are incomplete ?. 
4. Iam next to consider the position of wings in repose 
and their folding. The most important object of this is 
that when unemployed they may occupy less space, be 
less in the way of the insect, and be most effectually pro- 
tected from injury. Another end is also served by this 
structure,—that wings can thus be very ample, and pre- 
sent a large surface to the action of the atmosphere with- 
out incommoding the insect when it has not occasion to 
use them. . 
With respect to this head, insects may be divided into 
two classes—namely, those whose wings in repose are 
covered by wing-cases harder than the wings themselves, 
and those that have no such protection. In the former 
the wings, though the rule admits several exceptions, have 
more folds than in the latter. As the different mode of 
folding the wings has been assumed for a characteristic 
of the earlier Orders, I shall explain to you with as much 
brevity as possible how each is circumstanced in this re- 
spect, beginning as usual with the Coleoptera. 
There are ¢wo principal folds of the wing in this Order, 
which may be named the anal and the apical : the for- 
mer is when the Anal Area or part of it is folded on the 
under surface of the base of the wing ; this fold is always 
more or less longitudinal: the latter, the apical fold, is 
by means of the commissura or joint of the postcosta lately 
mentioned: which in Hister, Staphylinus, &c., for obvious 
reasons‘ is nearer the base of the wing; in Necropho- 
* Leach on Eproboscideous Insects, Mem. Wern. Soc. 1817. t. xxv. 
f.3, 5, 8, &e. > Ibid. t. xvi. f. 7, 10, 13. 
“ Insects with short elytra of course must fold their wings nearer 
the base than those with /ong ones. , 
