EXTERNAL ANATOMY OF INSECTS. 627 
wards*; others again are insulated, or do not originate 
from the base of the wing, or from other nervures, but 
are merely placed to strengthen an open space of it®: » 
these nervures are also usually broader and more sub- 
stantial than those of the wings of the subsequent Orders. 
Another striking circumstance with regard to them is 
that the nervures form few or no closed areolets, except 
in the Costal Area, where they are inconspicuous; in 
Dytiscus marginalis, indeed, and Tenebrio Molitor one 
or two may be found, but in general there are none. In 
many of this tribe the postcosta, which terminates at the 
joint of the wing, becomes recurrent, so as to form a 
hook, which perhaps represents the stigma, as in Dy- 
nastes©; in Creophilus, a rove-beetle, there is no hook 
but a broad plate adjacent to the costa. In the Strepsi- 
ptera Order the neuration is extremely simple, the ner- 
vures, except one insulated one, diverging from the base 
of the wing ¢: in this respect, as well as in the form of 
that organ, an approach is made to the Orthoptera. In 
the Dermaptera this approach is still more evident; in 
the common earwig °, the diverging nervures become 
numerous ; between each is an insulated one, taking its 
origin in the middle of the wing, and running to the 
margin; a little nearer to the latter all the nervures are 
dilated into a plate; those of the anal area are angular *, 
and the exposed part of the costal is as hard as the elytra. 
The neuration in the Orthoptera Order may be called 
radiate, the longitudinal nervures for the most part di- 
verging from the base of the wing like rays : in some few 
* Prats X, Fic. 4. 1. > Ibid. a. * Ibid. 0”, 
4 Pyare II. Fic. I, Comp. Linn. Trans. xi. t. ix. f. 1. 
© PraTeE X, Fic. 5. f Ibid, 2°, o, p*. 
Tine 
