Soitnd-prodiiction in the Lamellicorn Beetles. 738 



single fold fits into a rather deep pit so that additional 

 rigidity is secured. The part of the wing overlying tlie 

 spinose boss is in this region, and it is here that very 

 short erect spines are found upon the wing membrane. 

 As in Bolhoccras, the primary use of the wings remains 

 quite unaffected in the North American species uf Fassalns 

 (P. cornutus) studied by Mr. Babb, and indeed in the great 

 mnjority of the family, all of which probably have musical 

 powers; but in various Tropical American genera the 

 wings have become quite useless for the purpose of flight 

 and undergone a further development for the new func- 

 tion. They are reduced to narrow strips of stiff leathery 

 membrane shorter than the elytra. In Froculcjtcs and 

 some other related forms the hinge and the small spine- 

 bearing area just behind it are present, but the whole of 

 the wing beyond has disappeared, and the hinge having 

 lost its use is no longer movable. This strange trans- 

 formation has reached its furthest development in the 

 three great species forming the Central American genus 

 Proeulus, to which my attention was first directed by Dr. 

 David Sharp. The hinge has entirely vanished, and the 

 wing-remnants are quite opaque and straight and lie in 

 depressions in the elytra. These depressions are deeper at 

 the posterior part, and the corresponding part of the wing- 

 strip has its margins thickened above, so that the inter- 

 vening part of the membrane is slightly raised and forms 

 a drum. To use a more precise parallel the whole device 

 forms the resonating box of the fiddle. The outer (or 

 lower) side of the stretched membrane bears closely-set 

 pointed teeth of conical shape. The corresponding 

 abdominal bosses are similar to those of less profoundly 

 modified members of the group, and indeed have practically 

 the same form throughout the family. 



We can only conjecture what manner of sound is gener- 

 ated by this remarkable apparatus, for of the numerous 

 collectors who have captured the insects, in this case 

 larger than the largest beetles of our own country, none 

 has given any account of its habits. As regards the 

 smaller forms with normal wings belonging to Phoronwus 

 and related genera, Dr. Ohaus has supplied the defici- 

 ency, having published in the " Stettiner Entomologische 

 Zeitschrift" for 1900 (p. 164) an account of his observa- 

 tions in Brazil, which constitutes one of the most 

 interesting contributions made for many years to our 



