MALLARD. 



369 



to the tracheal tube ; but the column of air on the left side, 

 on passing through the bronchial tube is opposed by the 

 descending edge, and being divided by it, a portion is sent 

 in circles round the inner surface of the cavity before it 

 becomes united with the air from the other lobe in the tube 

 common to both. A compound tone of voice is thus pro- 

 duced by which wild-fowlers can distinguish males from 

 females of the same species, in the darkest night, whenever 

 the birds utter their note, as they frequently do, apparently 

 for the purpose of keeping together. Gilbert White of 

 Selborne, with his usual discrimination, says, in his forty- 

 third letter to Daines Barrington, which is devoted to the 

 consideration of the notes and language of birds : — " amono- 

 Ducks the sexual distinction of voice is remarkable ; for, 

 while the quack of the female is loud and sonorous, the 

 voice of the Drake is inward, harsh, feeble, and scarce dis- 

 cernible." 



The resemblance in the vignette below to the reed or other 

 mouth-piece, and the edge opposed to its inner orifice to 

 produce vibration in some musical wind instruments, will 

 be obvious. 



VOL. IV. 



3 B 



