STATES OF INSECTS. 331 



female than in the male a . In the genus Blaps F., the 

 mucro that arms the apex of each elytrum is longer in 

 the former sex than in the. latter. In AteucJms gibbo- 

 sus F., 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 en- 

 larged 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 Cicadce b . The wings of some but- 

 terflies, and of most moths and hawkmoths {Sphinx L.), 

 are furnished 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 Gioma c . 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 d . 



The other instruments of motion, the legs, also differ in 

 the sexes. In some instances they are disproportionably 

 long. This is particularly the case with the anterior pair 



a De Geer iii. 308. b Sec above, Vol. II. 394—. 



c Linn. Trans, i. 145. 135—. 

 d Ibid t xiii.y. 1. 2. <? . 3. $ . 



