ORGAN OF HEARING, : 115 



sorts of birds will mute if they are approached, and 

 it appears the arctic-gull profits by the knowledge of 

 this. We have at this moment a black- cap (^Sylvia 

 atricapilld) in a cage, who invariably mutes every 

 time any one comes near him, and the red-breast {S. 

 rubeculci) may be observed to do the same when he 

 is frightened away from his crumbs at the cottage 

 door. That it is the same in the case of the ants and 

 aphides any one may prove, by taking a pin or a 

 camel-hair pencil, and gently touching the aphis, 

 when it will eject the honey-dew as readily as by the 

 caressing of the antennae *. 



In many insects it is obvious the antennae cannot 

 be employed as organs of touch, on account of their 

 peculiar conformation. In the common flies {Mus- 

 cidce), for example, they are very short, and in some 

 of the beetles cannot be bent to the plane upon 

 which they walk. The great importance of the organ, 

 however, to beetles and some water insects is proved 

 by the care taken to protect it, and the manner in 

 which it is employed. In the water-scorpion (Be- 

 lostoma) there is a cavity in the head, containing a 

 very deep kidney-shaped box between the eye and 

 the throat, to receive and defend its singular antennae, 

 which, when they are reposing, is closed by the ex- 

 terior harder joints, and from which it seems as if 

 they turned out like a sentinel out of his box. In 

 some water-beetles (Gyrinus, Panius, Sfc.) they 

 are withdrawn within a lateral cavity of the same 

 part, and are defended from the water externally by 

 the auricle at their base. When a beetle rouses itself 

 from repose, the first thing it uniformly does is to 

 expand its antennae, which are usually kept in active 

 motion till it stops again, for the purpose as it seems 

 to us, not of feeling its way, because they seldom touch 

 anything, but of listening to the approach of enemies 

 or of prey. 



* J,R. 



