98 



CYGNUS NIGRICOLLIS. 



( 'ijg. — Albus ; capite colloque atris. 



BLACK-NECKED SWAN. 

 White swan ; with the head and neck black. 



rr. in. in. 



Length 4 2 Bill 3f 



White swan ; with the head and neck black; hill black, with two knobs at the base; legs 



orange. 



Anas nigricollis Gntcl. Syst. Nat. 1 . 51 12. 



Lath. Ind. On/. 2. 834. 



Anas melanocephalus Gmel. Syst. Nat. 1 . 502. 



Cygnus nigricollis Steph. Sh. Zool. 12. 1 7. 



Anas melancorypha Moll. French edit. 213. 



Inhabits the Falkland Isles and the Straits of Magellan. 



CYGNUS BEWICK! I. 



Cyg. — Albus: rostro atro, baso usque ad nares aurantiaco. 



BEWICK'S SWAN. 

 White swan ; with the hill black, the base orange to the nostrils. 



FT. IN. IN. 



Length - 3 101 ram 4^ 



Bill 3| Middle toe 5 



White; with the bill black, the basal half yellow, the yellow marking truncated at the ex- 

 tremity ; legs and toes black. 



Cygnus Bemickii, and trachea Yiarr. Linn. Trans, vol. 1". 



Eyton, Hist. R. Brit. Birds, p. 86. 



Discovered by Mr. Yarrell and Mr. R. Wingate to be an inhabitant of the British isles. 



The trachea of this species during youth penetrates the keel of the sternum in a similar manner 

 to that of C. ferns, but may always be distinguished by the greater length of the bronchia-. A 

 the bird approaches maturity the tube at the internal extremity of the portion penetrating the 

 sternum takes a horizontal twist, increasing in size and the depth to which it penetrates with age. 



The tube of the trachea is acted upon by two pairs of muscles, the first pair sterno-t radical, 

 the other having their attachment on the membrane stretched between the rami of the os fit real tun 

 and the sternum. ( Vide Jig. ) 



