Sound-production in the Lamcllicorn Beetles. 731 



here we meet with an entirely new and most interesting 

 type of organ. The jaws have no stridulatory surface, 

 but the legs bear structures elaborately adapted to the 

 purpose. If a larva of Geotntpes is taken between the 

 fingers it will invariably begin to fiddle, and, although its 

 note is only audible to the human ear at a short distance, 

 the means by which it is produced is easily seen by close 

 attention to its movements. Every note is accompanied 

 by a jerking movement of the last pair of legs straight 

 forward and against the bases of the second pair. The 

 last pair are reduced in size and, from the change they 

 have undergone in the manner of their articulation in order 

 to perform the forward movement, have probably ceased 

 to have any other use. Indeed, the larvae of Lamellicorns 

 in general have little use for their legs, commonly lying 

 on their sides in a doubled-up condition among the root 

 fibres, rotten wood, or other substance upon which they feed. 

 A modification of the legs for the performance of a new 

 function is therefore attended by no corresponding disability. 

 The joints of these modified legs seem to have retained little 

 power of separate movement, but extending from base to 

 tip on the inner side is a row of very hard sharp-pointed 

 prominences or teeth. This represents the fiddle-bow, 

 while the strings are formed by a beautiful series of fine 

 ridges occupying a pear-shaped area on the coxa of each 

 of the two intermediate legs. These ridges, according to 

 Schiodte, are very complex in their microscopic structure, 

 being finely serrated at their edges. 



Although this apparatus of the Geotrupes larva shows 

 a great degree of modification of the hind-legs, in another 

 family, the Passalidas, these have undergone a much 

 further development. This family of beetles, although the 

 extraordinary facts of their economy are as yet scarcely 

 known, is among the most remarkable of Insect groups. 



The larvse of Passalidaj, unlike those of all other known 

 Lamelhcornia, are active, the body being straight instead 

 of curled, and the legs are long, enabling them to walk at 

 a fairly quick pace. At first sight these exceptional larvse 

 appear to be quadrupeds, a careful examination being 

 necessary for the discovery of the traces of the third pair 

 of legs, which are reduced to a pair of tiny appendages 

 ending in four or five claw-like processes, and in some 

 species having a curious resemblance to a pair of out- 

 spread hands. They lie close to a minutely-ridged area 



