ANSEKES 



463 



flexor profundus ; in Biziura lobata 

 the same slip is given off, but it be- 

 comes lost on one of the annular masses 

 of fibrocartilage surrounding the other 

 flexors. 



The windpipe in the Anseres is nearly 

 always straight, the only exception 

 among the ducks and geese as yet 

 recorded being Anseranas melanoleuca, 

 in the males of which the trachea forms 

 a double loop, extending to quite the 

 end of the pectoral muscles. A 

 second peculiarity of the trachea is 

 seen in the males of Metopiana pepo- 

 saca, Strictonetta ncevosa,^ Melanitta 

 fusca, Nyroca, Mergus, Somateria, and 

 Clangula. In these (see fig. 222) there 

 is ^ bulbous enlargement of the trachea 

 some little way in front of the syrinx. 

 It is present, but very slightly developed, 

 in Fuligula rufina. In nearly all the 

 ducks the syrinx in the male has a re- 

 markable asymmetrical enlargement, 

 which is as a rule entirely bony, but is 

 sometimes {Mergus, Clangula, Nyroca, 

 Fuligula) mainly formed of membrane. 

 The accompanying figures will give 

 some idea of the form of this structure, 

 which shows differences in different 

 species. The figures are taken from 

 a memoir upon the subject by Professor 

 Gaeeod.2 Yaeeell ' and Eyton'' have 



' E. P. Eamsay, ' Note on the Trachete of certain 

 Australian Ducks,' Proc. Lmn. Soc. N. S. W. iii. 

 1879, p. 164. 



^ ' On the Form of the Lower Larynx in certain 

 Species of Ducks,' P. Z. 8. 1875, p. 151. 



' British Birds. 



* Monograph of the AnatidcB or Duck Tribe. 





JFia. 222. — Windpipe of 

 Metopiana peposaca S 

 (after Gaeeod). 



