StricLiitating Organs in Goleoptcra. 445 



crenulate, edge of a plate forming part of the middle coxa, 

 the action beinsj much the same as when the edge of one 

 lile is drawn obliquely across the edge of another. The 

 larvae of Passaliihv practically have but two pairs of legs ; 

 for the hind-legs, though present, are as legs almost 

 absolutely functionless, and seem to be used only for the 

 purpose of producing sound. These legs are very greatly 

 reduced in size, being only just sufficiently long to reach 

 forward as far as the coxa^ of the middle legs and scrape 

 the transversely ribbed areas which are specially situated 

 there. In the forms described by Schiodte each of the 

 hind-legs is narrowed towards the apex, and furnished 

 there, as well as on its anterior face, with special rasping 

 teeth ; but in other forms, one of which has been figured 

 nnd described by Dr. Sharp in the "Cambridge Natural 

 History," each of these legs resembles a paw, the rasping 

 teeth being spread out in a row at the apex. 



The profound modification which the hind-legs have 

 undergone, apparently in order to become more efficient as 

 sound-producing organs, suggests that stridulation has 

 some important bearing in the life of these larvce. But 

 as the larva? live concealed in burrows made by eating 

 through the decaying wood of old stumps or trunks of 

 trees, it seems unlikely that stridulation can be of much, 

 if any, use in protecting them from their enemies. Then 

 what is its use ? My colleague, Mr. Waterhouse, has 

 suggested to me that, with a number of larva? living close 

 together in the way described, it would be an advantage 

 to each to be left in undisturbed possession of its burrow, 

 and to eat its way in such a direction that it would not 

 cross the path of another. Stridulation as a means of 

 effecting this becomes useful to the larva?. Acting as 

 a sort of declaration of each individual's rights, it would 

 tend to promote general harmony. This suggestion as to 

 the use of the stridulating organs will, however, scarcely 

 apply to the larvte of the Gcotruindx, since these larva?, 

 which live at souie depth underground, are not, so far as I 

 know, usually met with living in close proximity to one 

 another. But every other suggestion I have heard seems 

 to offer as great or even fjreater difficulties, and I fear that 

 the precise use a.ud meaning of these organs will for some 

 time longer remain a mystery. Judging from what I have 

 seen of them in the larvae of Lucanus ccrvtis, the stridu- 

 lating organs seem to be developed at a very early stage, 



