27-t '^'^y 



The formation of the palpi in our indigenous Sesia fuciformis, 

 and the faint sound produced when they are rubbed on the haustellum, 

 would lead one to think a musical organ must be looked for in the 

 Sesiidce, placed as in Acheronfia. 



In the Bombycina, next in review, the rule appears general that 

 the capability for stridulation is greater in the male sex, the organs 

 by which it is produced having in it the greatest development. Many 

 species possess a high degree of susceptibility, and pertinaciously 

 sham death in the net, while the pervading brightness of their colour 

 seems to negative the law pertaining to the OrtJioptera-Saltatoria, 

 where, as a rule, a dulness of hue indicates an increase in the capacity 

 for music in a species. The organism by means of which these moths 

 produce, or probably produce, a stridor, consists in a little triangular 

 bladder, external, denuded of hair and scales, or virtually so, formed 

 simply, it would appear, by a vesicular dilatation of the integument 

 of the episternum of the metathorax, over the surface of which runs a 

 lenticular crumplinq representing a lima, placed vertically, and lying 

 invariably in the depression on its tense membranous superficies, that 

 receives the inioardly bowed hind femur (which, in its position of repose, 

 is adducted to the thorax), the inner superficies of which, often in 

 part semi-denuded, is so directed as to suggest its function of effecting 

 a stridor. The complete apparatus invites comparison with the inflated 

 abdomen of the male Orthoptera of the genus Pneumora, and its semi- 

 circular row of rectangular tubercles placed on either side of the 

 third segment, that give rise to a stridulous sound or friction, when 

 incited by the oscillatory movement of the hind femora. Or it may 

 be paralleled with the spherical tymbals on the upper surface of the 

 first dorsal arc of the abdomen of the male Gicadce, traversed by raised 

 chitinous stria), which effect the drumming notes (if I may draw 

 inference from analogy, certain considerations of adjustment and 

 organization, method of singing, &c.), by scraping over a salient portion 

 of the chitinous integument posterior and adjacent, worked by an 

 internal muscle described by Eeaumur, aided by a vertical and lateral 

 movement of the agitated abdomen. (Compai'c on this subject papers 

 by Solier and Goureau, Ann. de la Soc. Ent. de France, 1837-38). 



The vesicular bladder, often conspicuous in the Heterocera, was 

 discovered by Solier in Chelonia pudica, and advanced as adequate 

 explanation of the sound this insect was heard to produce on the 

 wing (Ann. de la Soc. Ent. de France, t. vi). It was noticed to bear 

 stria) on its anterior margin both by Solier and Laboulbene, about 

 sixteen to twenty in the male, and eight to ten in the female, some 

 six of \vhich are more elevated than the remainder. The latter author, 



