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XXVII. Sound-production in the Lamellicorn Beetles. 

 By Gilbert John Arrow, F.E.S. 



[Read October 5th, 1904.] 



Plate XXXVI. 



A SUMMARY of our knowledge of the vocal organs of 

 beetles was published by Mr. C. J. Gahan in the Trans. 

 Ent. Soc. Lond. for 1900, and many new observations of 

 the greatest interest recorded. In this memoir ten genera 

 of the great Lamellicorn group w^ere described as possessing 

 vocal powers in the adult stage, and in addition to these 

 certain other beetles of the family Dynastidse not 

 enumerated by Mr. Gahan were known to stridulate. 

 Since 1900, however, various fresh and interesting observa- 

 tions on the subject have appeared in foreign publications, 

 and my own study of these beetles has brought to light 

 vocal structures as yet undescribed and revealing the 

 existence of the faculty in new groups. The variety of 

 the structures serving the purpose in the Lamellicorniaand 

 the remarkable fact of the occurrence, so far unknown in any 

 other beetles, of highly-developed stridulating organs in 

 the larvse, render these the most remarkable in regard to 

 vocal powers of all insects, and, although our knowledge of 

 the organs is no doubt still very incomplete, the additions 

 made to it in the last few years are, I think, quite 

 sufficient to justify the present attempt to set forth all 

 that is at present known on the subject. 



As to the stridulation of larval Lamellicornia, little more 

 has been discovered since the remarkable work of Schiodte 

 was published in 1874 (Naturhistorisk Tidsskrift, Ser. 3, 

 vol. ix), but many additional genera are here enumerated 

 as stridulators in the perfect state, and, although the faculty 

 seems much less general in that stage, the list will no 

 doubt yet be considerably increased. 



The special importance of stridulation in the Lamelli- 

 corns is probably in part due to a mental development 

 higher than that of most other beetles and evidenced, not 

 only by the concentration which here occurs in the nervous 



TRANS. ENT. SOC. LOND. 1904. — PART IV. (dEC.) 46 



