The Cerambyx-beetles have another method, likewise based on friction. The Great Capricorn, for instance, moves his corselet over its junction with the thorax. There is here a large cylindrical projection which fits tightly into the cavity of the corselet and forms a joint which is at the same time powerful and mobile. This projection is surmounted by a convex surface, shaped like an heraldic scutcheon, perfectly smooth and absolutely devoid of any sort of fluting. This is the musical-box. The edge of the corselet, itself smooth inside, rubs over this surface, passing to and fro with a rhythmical movement and thus creating a sound which is once more like that of a window-pane rubbed with a moistened finger. Still, I am unable to make the dead insect’s apparatus sound by moving the corselet myself. Though I hear nothing, I at least feel with my moving fingers the shrill vibration of the surfaces rubbed. A little more and the sound would be audible. What is lacking? The stroke of the bow which the live insect alone is able to supply. We find the same mechanism in the small Capricorn, Cerambyx cerdo, [57] and in the denizen of the willows, the Rose-scented Aromia, A. moschata. [58] On the other hand, the Ægosoma and Ergates, mighty Longicorns both, are without the projection fitting into the corselet, or rather possess of it only as much as is strictly necessary to join the two parts together. Consequently the two big night-insects are dumb. Though we are acquainted with the simple mechanism of the Cockchafer’s instrument, its employment none the less remains a riddle. Does the insect use it as a means of nuptial appeal? This is likely. Nevertheless, I have not heard the slightest grating on the pines, in spite of all my attention at propitious hours. I have heard nothing either in the cages, where distance formed no obstacle to the hearing. If we would make the Cockchafer squeak, all that we need do is to take him in our fingers and tease him a little. The sound box works at once and does not cease until we do. What we now hear is not a song but a complaint, a protest against misfortune. It is a singular world in which sorrow is translated by couplets and joy by silence. The other scrapers of the abdomen or corselet behave in like fashion. When surprised upon her pills, at the bottom of her burrow, the mother Copris groans, for a moment bewailing her fate: the Bolboceras, held captive in the hand, protests with a gentle elegy; the Capricorn when caught sets up a desperate grating. All are mute as soon as the danger is past; all likewise persist in their silence when absolutely at rest. I never knew any of the three to sound his instrument apart from the alarm to which I subjected them.