2'20 ANATOMY OF VEIITEBKATES. 



forming a conical trachea, as in tlie Turkey, the Heron, the Buz- 

 zard, the Eagle, the Cormorant, and the Gannet ; or they may be- 

 come wider by degrees to the middle of the trachea, and afterward 

 contract again to the inferior larynx ; or lastly, they may experience 

 sudden dilatations for a short extent of the trachea ; the Golden-eye 

 {A?ias clangula), the Velvet-duck (A?ias fusca), and the Merganser 

 {Mergus serrator), present a single enlargement of this kind, in 

 which the bony rings are entire, and of the same texture as in the 

 rest of the tube. In the Golden-eye the trachea is four times 

 larger at the dilatation than at any other part. In the Goosander 

 {3Iergus merganser^, the trachea presents two sudden dilatations 

 of a similar structure to that above described. The trachea of the 

 Emeu ( Dromaius ater^ is also remarkable for a sudden dilatation, 

 but in this instance the cartilaginous rings do not preserve their 

 integrity at the dilated part, but are wanting posteriorly, where 

 the tube is completed by the expanded membranes only. 



With regard to the windings of the windpipe, in an Australian 

 Snipe {Rhynchma australis), the convolutions, which are short, 

 are external to the chest, between the skin and the fore part of 

 the pectoral muscles. In the same position lie the long double 

 coils of the windpipe in the Semipalmate Goose {^Anas semi- 

 palmatci), and the long single fold in Ortalida Parraqua. In the 

 Crested Pintado {Numida cristata), the apex of the furculiun 

 forms a bony cup which receives a loop of the trachea. In the 

 crestless Guan (^Penelojje Mirail), the Demoiselle {G?'us virgo), 

 and Stanley Crane ( Grus Stanley anus), the trachea forms a curve 

 sinking into the upper and fore part of the sternum. In the com- 

 mon Crane (^Grus cinerea^, and Serass Crane {Grus Antigone), the 

 keel of the sternum is more deeply hollowed for the lodgment of 

 more extensive coils of the trachea. In the male wild Swan 

 (^Cygnus ferus^, the windpipe describes a double vertical coil 

 within the long and deep keel of the sternum : in Bewick's Swan 

 ( Cygnus Bewickii), the distal part of the coil lies horizontally 

 within the body of the sternum : the entry and exit of the intra- 

 sternal coils are shown in fis^. 101. 



§ 159. Lower Larynx in Birds. — The main or essential organ 

 of voice is situated at the bifurcation of the trachea, ib. a, into 

 the bronchi, ib. b, h ; and herein may be discerned an analogous 

 relation to convenient stowage, which the jiosition of the mas- 

 ticatory apparatus shows : for even the muscles of the organs 

 of voice and the bony drum of the larynx, &c., are brought 

 beneath the centre of gravity, at the base of the neck, not accu- 

 mulated at its anterior extremity. In general tlie rings of the 



