INSECT VAMETY. 243 



Giyllidae, reputed mute, want the tibial organs. Some o£ these 

 ai5j)ertaining to the former group are apterous ; others have no 

 musical vein ; and one has corneous elytra. As regards the Leaf 

 Crickets, these organs are absent in some, and these very species 

 are those that want the serrated elytral vein and talc-like spots. 

 I may mention lastly, in conclusion, that as regards experimental 

 proof of the employment of these cavities for hearing, I have 

 noticed that the male Great Green Leaf Cricket, when it ])er- 

 forms, extends its fore-legs, as has struck me, in order to adjust 

 these cavities, and receive the music of its rivals (Plate IIL, 

 Fig. 3). 



ORGAN or HEARING IN THE LEI'IDOPTERA (PLATE IV., 

 FIGS. 6 AND 9). 



An ear will, at first sight, appear a superfluity in the butterfly 

 and moth tribe, whose males are not heard over the meadows 

 contending in song, and whose females are not noticed following 

 on the trail with meek attention. Nor, indeed, to supply the 

 requirements of the little obvious instrumental music present in 

 a few species, even when taken in conjunction with the pheno- 

 mena of wing-beating, would the general prevalence of an organ 

 of hearing in Lepidoptera be demonstrable, for the auditory 

 might be supposed supplanted by the other senses, as we have 

 seen the selective pageants of love and rivalry chiefly manifest- 

 ing themselves in other directions, such as the aggregation of 

 the males in alluring wing-dances, and the sedentary colour 

 display of the female, which would postulate an adaptation of 

 the visual rather than the auditory faculty ; or, again, the sexual 

 provision of odorous fans would have relation to the sense of 

 smell. But, on the other hand, in seeking for an auditory 

 organ protective and generally intimative, we have greater 

 prestige, especially among the dull night-flying groups, where 

 we find the many-faceted eyes small and disadvantageously 

 placed, though phosphorescent at night and sensitive. 



However this may be, a counterpart of the auditory structure 

 of the grasshoppers may be found in Lepidoptera, corresponding 

 in parts and structure, save that we find often here an adjunct 

 of empty convoluted cells, parted with mirror-like membranes, 

 which, from their introducing air behind the abdominal cavity, 

 Q 2 



