260 The entomologist's record. 



the noticeable structural difference of these organs in the grasshoppers 

 and locusts by the difference in the relative position of the tegniina, 

 legs and abdomen, which we notice in representatives of the two 

 families. But such an explanation can hardly be accepted, since it is 

 not likely that, in the gradual perfection of the sounding organs, the 

 parts bearing and adjacent to them did not participate. On the 

 contrary, it seems to me, that, in order to strengthen the sound, the 

 abdomen and tegmina should have somewhat changed their original 

 position, and that the position of these parts in Orthoptera, as we see 

 at the present time, is essentially the result of such an adaptation, ?.c., 

 a later appearance and not preceding the formation of the stridulating 

 organs. It is not hard to be convinced of this if we examine the 

 wingless forms that are found in considerable numbers among the 

 grasshoppers as well as locusts. As to the cause favouring the difference 

 in the formation of the stridulating organs of the grasshoj^pers from that 

 of the locusts, I am of opinion that the bright colouring of the hind-legs, 

 exclusively a peculiarity of the grasshoppers, constituted the principal 

 cause of this difference. The fact is, we know already, that insects 

 always try to expose the bright colours of their body (especially since 

 the bright colours constitute a secondary sexual character). We 

 know, for example, that the beautifully coloured wings of diurnal 

 butterflies are constantly in motion. The butterflies now raise, now 

 lower them at varying angles, which still more enhances the beauty 

 and brightness of the wings. We also observe almost the same 

 motion in Hies with coloured wings {Trjipctidae, < h-tali'lac) even 

 though they are more modestly coloured. These suiall Hies, walking 

 over the leaves and flowers of plants, now raise, now lower their 

 wings. The bright colours of the hind-legs elicited similar phenomena 

 in the grasshoppers. But here the motion of the legs had to be much 

 stronger, since the bright colours are distributed over the concealed 

 parts of the legs. In order to expose these parts the insects are 

 obliged to raise their legs high and turn them in all directions. To 

 what an extent the hind-legs of grasshoppers are movable, and what a 

 variety of motions they perform, are easily observed in the males of 

 the genera Staitrojidtn.^ and Stem iboth nix, when in captivity. Nothing 

 of this kind is observed in locusts, neither are the hind-legs coloured. 

 Under such constant motion of the hind-legs (when the insect is not 

 aware of danger and is in the presence of a female) the grazing of the 

 ends of the tegmina with the moving legs is evidently a phenomenon 

 next in order ; the sounds thus produced, even though weak, served 

 the purpose of sexual selection, which gradually intei'-fitted the sound- 

 producing parts of the body of the insects for the strengthening of the 

 sounds. 



There is no foundation whatever for thinking that the bright 

 colours of the hind-legs of the grasshoppers could have appeared after 

 the formation of the rasping organs and together with them the teg- 

 mina. On the contrary, it can be absolutely asserted that the colour- 

 ing of the hind-legs preceded the formation of the wings. The best 

 proof of this is furnished us by the wingless forms, and among them 

 the above described Xacanxli's ci/cdiiiics, in which, notwithstanding the 

 entire absence of even the vestiges of wings, the hind-legs are 

 exceptionally brightly and peculiarly coloiired. We should sooner 

 look for relations between the absence of means of stridulation in the 



