Stridulating Organs in Coleoptera. 437 



seem clear; it can scarcely act as a scraper, an inwardly 

 projecting rim at its base where it joins the iDrouotum 

 appearing to serve for that purpose. It may possibly be 

 set in vibration, and serve to augment or modulate the 

 sound produced by tlie scraping of the file on the head. 

 A somewhat similar but less conspicuous modification of 

 the anterior edge of the pronotum occurs in both sexes of 

 Edigmcna and other genera of Hispidm and in nearly all 

 of the stridulating species of Emlomycltida}, appearing in 

 most in the form of a small pit or depression such as is 

 described by Mr. Gorham in his reference to the stridu- 

 lating organ of Eiicymon ruficoUis, Kirsch. 



The stridulating area in Estigincna chincnsis is divided 

 into two parts by a short depressed interval, the anterior 

 being much more finely striated than the posterior part, 

 thus by its structure seeming capable of producing a very 

 much higher note when rubbed by the edge of the pro- 

 notum. In His2M2rria foveicollis, Baly, the stridulating 

 area is still more complex, consisting of three parts (PI. 

 VII, figs. 3 and 3rt) ; the part in front, forming the apex of 

 a triangular area, is very finely striated, and is followed 

 behind without any break by an area in which the striae 

 are much coarser and less approximate to one another; 

 this area is succeeded by a pit-like depression, behind 

 which there is a short space presenting a fairly regular 

 transverse striation somewhat intermediate in character 

 between the other two. Equally complex is the condition 

 existing in Anhodcra scutcllata, Baly, the striated area on 

 the head being similar to that of Hisijopria with this 

 difference only, that the three parts of the area are divided 

 from one another by shallow transverse depressions. 



From the structure of their stridulating apparatus it is 

 to be inferred that these beetles can and do produce 

 sounds of at least two different degrees of pitch (and 

 probably of three), one being about an octave higher than 

 the other, while further the possibility has to be admitted 

 that by the requisite movement of the head, the beetles 

 might be able to vary the order or succession of the notes 

 in such a way as to give rise to several simple musical 

 airs. 



Unfortunately no observations have yet been recorded 

 in reference to the nature of the sounds made by the 

 living insects, and although it is very unlikely that such 

 obsetvations will prove the sounds to be so varied as the 



