36 Account of Observed Forms of Larynx. 



J 



The birds with a tracheal orgaa of voice, which I shall henceforward merely call 

 TracJieojjJiones, are famous for their marvellous voices. Azara already has called the voice 

 of the Batara [Thamnophilus) marvellous and strong ; it consists in the continual repe- 

 tition of the syllable ta, and can be heard half a mile off ^. Prince Max speaks of the 

 simple but marvellous voice of a TUamnopliilus ; the same author calls the voice of Furnarius 

 very loud, and marvellous, although composed of few tones. Darwin mentions the pecu- 

 liarly shrill, rapidly repeated voice of Furnarius ^. According to Azara the voice of 

 the Oven-Bird is heard half a mile off^. According to Swainson Synallaxis has a loud, 

 and very unpleasant voice. Prince Max mentions the fine high tones of Tinactor, 

 Darwin the loud cry of Scj/(alopns mar/ellanictts*, and the strange barking tones of 

 PterojdocJms^. According to Kittlitz, the tones oi Plerojdochus paradoxus are very high, 

 more like the voice of a frog than that of a bird. Prince Max calls the voice of Analates 

 erythroplitlialmus loud and marvellous. 



Grallaria tiniiiens {Turdus tiuniens L.) is famous for its bell-like voice ; this state- 

 ment of Vieillot and BufTon arises perhaps from some mistake, for no later observer 

 has confirmed it. Moreover, one cannot expect a voluminous voice in any bird with 

 a tracheophone vocal organ, for no means of producing it are present in this struc- 

 ture. I have never found large vocal bands, although I have continually made sections 

 of this larynx ; their vocal capacity is reduced to the mere vibrations of the membranous 

 portion of the trachea, the walls of which are thrown into folds by the action of their 

 muscles, and set in vibration by the stream of air. 



All the TracheopJiones form together one large family, and break up, in it, into 

 several groups. All are distinguished by short rounded feathers, some by long feet, some 

 by short tails. The extremes, Thamnophllus and Bendrocoiaptes, are considerably different, 

 although they are completely united by intermediate steps; the stifi" and long shafts 

 of the tail feathers of Bendrocolapies are arrived at step by step, through the genera, 

 Si/nallaxis, Anahates, and Tlnarlor. 



This family with its subgenera contains, as yet, only South Amei-ican forms. 

 Further examination is needed to show whether the Orihoni/x Temm. of New Zealand is 

 connected with the American Deiidrocolapdae or no. The East Indian MfiopJwnus, Timalia, 

 and so-called Ant-Birds of the Old World are not allied to the Mfiotherae of the New, and 

 belong rather to the Singing Birds. 



' Apuntiamentos, II. p. i86. ^ Zool. of H.iM.S. Beagle, III. 64, 65. 



= Loc. cit., II. p. 223. * Loe. cit.. III. p. 72. 



'" Darwin Naturwissenschaftl. Reisen II. 22, 23, 45. 



