330 STATES OF INSECTS. (Jmago.) : 
the hemelytra and wings are narrower and shorter in the 
female than in the male*. In the genus Blaps, the mu- 
cro that arms the apex of each elytrum is longer in the 
former sex than in the latter. In Ateuchus gibbosus, a 
dung-beetle, the elytra have a basal gibbosity near the 
suture in one sex that does not obtain in the other. In 
the Orthoptera order the sexes are often to be known, 
almost at first sight, by a difference in the veining and 
areolets of the wings; but upon this I enlarged so fully 
when I treated of the sounds produced by insects, that 
it is not necessary to repeat what I have said ;. which 
observation also applies to the drums which distinguish 
the male Cicade”. ‘The wings of some butterflies, and 
of most moths and hawkmoths (Spiznx L.), are fur- 
nished with a singular apparatus for keeping them 
steady, and the under-wing from passing over the upper 
in flight. ‘This appears to have been first noticed by 
Moses Harris, and was afterwards more fully explained 
by M. Esprit Giorna*. From the base of the under- 
wing proceeds a strong bristle, received by an annulus or 
socket, which springing between the two principal ner- 
vures of the upper-wing terminates in the disk of the 
wing: in this annulus the bristle moves to and fro, and 
prevents the displacement of the under-wing. This ap- 
paratus is perfect only in the males, which alone have 
occasion for long flights; the females, though they have 
often several bristles, having no annulus*. 
The other instruments of motion, the legs, also differ 
in the sexes. In some instances they are disproportion- 
* De Geer iii. 308. » See above, Vor. II. 397—. 
© Linn. Trans. i, 145, 135--. 
© thi. 2S Fa ee 
