Soimd-po-ochcdion in the Lamellicorn Beetles. 729 



(PI. XXXVr, fig. dlj) with a lens sliows tliat the posterior 

 part (that is, all but a narrow anterior strip) of each of 

 the three segments preceding the terminal one has a 

 peculiar opaque surface, and under a high power it may 

 be seen that this is due to the presence, entirely confined 

 to these areas, of an immense number of short stout 

 chitinous spines, all directed towards the middle line of 

 the back, where there is a distinct parting. The spines 

 are sharply limited in their extent by a straight line a 

 little behind the front edge of each of the three seoments 

 to which they are peculiar. These do not come into 

 contact with the elytra, but are covered by the ratlier 

 voluminous wings, which when not in use are folded twice, 

 so that the outer margin of each approximately forms a 

 letter N, that of the left wing represented by the letter 

 reversed. The two wing-tips thus cover the end of the 

 back where the spiny areas are situated. Upon examining 

 tliis part of one of the wings under the microscope I dis- 

 covered a small patch of spines adjoining the costal vein 

 just before the extremity of the wing (PI. XXXVI, figs. 

 9, 9a). These spines seem very strong and rigid and are 

 quite different to those upon the back, much longer and 

 more scattered. They are evenly distributed, however, 

 and entirely confined to a small longitudinal strip, all 

 being directed backwards so that the instrument must be 

 operated by the end of the body being drawn across the 

 wing- tips from back to front, pressing them against the 

 elytra as a support to the delicate membrane. I have 

 found no trace of these remarkable wing-areas except in 

 Bolhoccras galliciim (the species heard by both Solier and 

 Fabre) and the two closely-related forms, B. ttnicorne and 

 hocchus. The sound produced by this means could hardly 

 be other than faint and soft as described by Fabre, antl 

 indeed had I not found the musical habit recorded I could 

 only have described these structures as musical in their 

 function with considerable hesitation. It is a further 

 satisfaction to me to have found additional confirmation 

 in the recently published observations of another writer, 

 Herr Verhoeff. In the " Sitzungsberichte der Natur- 

 forschenden Freunde zu Berlin " for 1902, Herr Verhoeff 

 records that he has found several species of Geotrupcs to 

 produce sound supplementing that of the coxal organs by 

 friction between the elytra and certain spinose areas upon 

 the dorsal surface of the abdomen corresponding with 



