( 709 ) 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
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