116 THE ANATOMY OF BIRD-SONG. 



study, since his falsetto in his wild state is 

 mostly a nocturnal performance. 



The sparrows, the thrushes, the meadow-lark, 

 and some of the warblers elevate their heads 

 (with their beaks at an angle of at least forty- 

 five degrees with the horizon) in singing. It 

 is by this attitude that they can give greatest 

 freedom to their throats. Other songsters, 

 including the orioles, the blue-bird, and most 

 of the smaller fry, utter their notes while in 

 any position, even on the wing. 



I have called attention to these extrinsic 

 features of the song-habit in birds because I 

 deem them of great value in determining the 

 voice functions of the trachea and syrinx of 

 the o seines. 



V. 



The most difficult question in our investiga- 

 tion arises out of the unmusical notes— the 

 quacks, croaks, jarring cries, and cackling 

 noises made by the birds when not inclined 

 to whistle. If, on one hand, a pure flute note 

 cannot be made by the vibration of the mi- 

 nute syringeal membranes of a mocking-bird, 

 it would appear, on the other hand, that a 

 hoarse, gutteral, rasping snarl could not be 

 originated by a whistling orifice, or, in other 

 words, by the glottis of a mocking-bird, a 

 crow, or a meadow-lark ; but a little attention 

 will clear iq) the trouble. When we are very 

 near the crow, for instance, his voice divides 

 itself into two distinct sounds, one a clear, 

 steady wind-note, the other a jarring noise, 

 harsh and disagreeable. The effect is the 

 well-known caw, sometimes successfully imi- 

 tated by a boy making a nasal sound in his 

 hollowed hands. The jarring or rasping ele- 

 ment of the crow s voice is really caused by 

 the vibration of a membrane, but it is not a 

 syringeal membrane. The note first made by 



