This is how De Geer (_Mémoires_, iii. 429) describes the sound-producing apparatus of the Great Green Grasshopper: ‘In our male grasshoppers, in that part of the right elytron which is folded horizontally over the trunk, there is a round plate of very fine transparent membrane, resembling a little mirror or piece of talc, of the tension of a drum. This membrane is surrounded by a strong and prominent nervure, and is concealed under the fold of the left elytron, which has also several prominent nervures answering to the margin of the membrane or ocellus. There is every reason to believe that the brisk movement with which the grasshopper rubs these nervures against each other produces a vibration in the membrane, augmenting the sound. The males in question sing continually in the hedges in the months of July and August, especially towards sunset, and part of the night. When any one approaches they immediately cease their “song.”’ It is probably unnecessary to do more than remark that the noises made by Insects do not correspond to the voices of the higher animals. ‘For no insect, like the larger animals, uses its mouth for utterance of any kind: in this respect they are all perfectly mute; and, though incessantly noisy, are everlastingly silent[26].’ Our plan with these wings is to first verify the fact of their bearing these talc-like spots, the serrated nervures on the right and the rudimentary file on the left elytron. The sound is produced by rubbing the base of the left elytron against that of the right. A recent author compares this insect to a fiddler, and says that the left tegmen is the bow and the right the fiddle. The last point to examine is the ear. It seems strange to say that these insects have ears in their legs; but though some of the older entomologists regarded these structures in the tibiae of the first pair of legs as nothing more than resonators or sound-boards to intensify their chirping, there is no doubt that they are really organs of hearing. Much interesting information on this subject will be found in Sir John Lubbock’s _Senses of Animals_. [Illustration: FIG. 40.--Tibial ear of Great Green Grasshopper.] These oval patches are plainly distinguishable by the unassisted eye, and correspond in function to the tympanum or drum of the human ear. The air-supply to the tibiae is distinct from that of the rest of the body, and is derived from a large orifice on each side of the first segment of the thorax. These orifices may be seen by removing the ‘hood.’ Indeed, they cannot escape observation. From these orifices an air-tube passes to each leg, dividing into two branches in the tibia and reuniting below the drums.