iv ANATIDAE I I I 



politan Family Anatidae, with the Swans, Geese, and Ducks ; 

 where, in spite of many attempts at subdivision, the lines of 

 demarcation cannot yet be finally determined. Count Salvadori, 

 however, having lately propounded a carefully-elaborated arrange- 

 ment, 1 I have adopted his Sub-families in the present volume, 

 viz. (1) Merginae, (2) Merganettinae, (3) Erismaturinae, (4) 

 Fidigulinae, (5) Anatinae, (6) Chenonettinae, (7) Anserinae, (8) 

 Cereopsinae, (9) Plectropterinae, (10) Anseranatinae, and (11) 

 Cygninae. 



The skull is short and robust ; while the neck is abnormally 

 developed, with extra vertebrae, in the Swans, and is usually 

 long, though less so in the Sea-Ducks ; in the Merginae and 

 some Fuligulinae the customary posterior notches in the sternum 

 are converted into two complete fenestrae or apertures. The 

 bill is almost entirely covered with a soft sensitive membrane, 

 ending in a horny process termed the nail, the skin being warty 

 in Anseranas and Chen rossi ; Cereopsis has a large tumid cere ; 

 both sexes of Cygnus melanocoryphus and C. olor have a knob 

 at the base of the culmen, as have the males of Plectropterus, 

 Tadorna cornuta, and the domesticated form of Cycnopsis 

 cycno'ides ; the same sex of Somateria spectabilis has the posterior 

 portion of the maxilla spread into a disk ; Oedemia has it con- 

 siderably swollen even in the female ; Cairina and Plectropterus 

 have caruncles on the forehead ; Sarcidiornis has a fleshy comb 

 at the proximal extremity of the beak in the male ; while Biziura 

 has a dependent flap on the chin, and a small subgular pouch. 

 The bill is usually broad and depressed, and may be sub-conical, 

 as in many Geese ; spatulate, as in Spatula and Malacorhynchus; 

 or somewhat less dilated, as in Chaulelasmus, and so forth. There 

 is a distinct hook at the tip in Mergus, Dendrocycna, and Aex ; 

 the culmen is concave in Marmaronetta and Stictonetta ; the nail 

 is bent inwards in the latter and Erismatura, while the maxilla 

 may overlap the mandible, or the covering membrane may even 

 hang over the latter, as in Malacorhynchus, Hymenolaemus, and to 

 a less extent in Elasmonetta and Nesonetta. The length is very vari- 

 able, but the thin elongated " sawbill " of Mergus, with its serrated 

 edges, is especially remarkable. Most characteristic of the Family 

 is the presence of highly-developed lamellae or transverse tooth-like 

 processes on both maxilla and mandible, which are visible when 



1 Cat. Birds Brit. Mus. xxvii. 1895, pp. 23, 24. 



