BREED 1. _Common Domestic Duck_.--Varies much in colour and in proportions, and differs in instincts and disposition from the wild-duck. There are several sub-breeds:--(1) The Aylesbury, of great size, white, with pale-yellow beak and legs; abdominal sack largely developed. (2) The Rouen, of great size, coloured like the wild-duck, with green or mottled beak; abdominal sack largely developed. (3) Tufted Duck, with a large top-knot of fine downy feathers, supported on a fleshy mass, with the skull perforated beneath. The top-knot in a duck which I imported from Holland was two and a half inches in diameter. (4) Labrador (or Canadian, or Buenos Ayres, or East Indian); plumage entirely black; beak broader, relatively to its length, than in the wild-duck; eggs slightly tinted with black. This sub-breed perhaps ought to be ranked as a breed; it includes two sub-varieties, one as large as the common domestic duck, which I have kept alive, and the other smaller and often capable of flight.[436] I presume it is this latter sub-variety which has been described in France[437] as flying well, being rather wild, and when cooked having the flavour of the wild-duck; nevertheless this sub-variety is polygamous, like other domesticated ducks and unlike the wild duck. These black Labrador ducks breed true; {277} but a case is given by Dr. Turral of the French sub-variety producing young with some white feathers on the head and neck, and with an ochre-coloured patch on the breast. BREED 2. _Hook-billed Duck_.--This bird presents an extraordinary appearance from the downward curvature of the beak. The head is often tufted. The common colour is white, but some are coloured like wild-ducks. It is an ancient breed, having been noticed in 1676.[438] It shows its prolonged domestication by almost incessantly laying eggs, like the fowls which are called everlasting layers.[439] BREED 3. _Call-Duck_.--Remarkable from its small size, and from the extraordinary loquacity of the female. Beak short. These birds are either white, or coloured like the wild-duck. BREED 4. _Penguin Duck_.--This is the most remarkable of all the breeds, and seems to have originated in the Malayan archipelago. It walks with its body extremely erect, and with its thin neck stretched straight upwards. Beak rather short. Tail upturned, including only 18 feathers. Femur and meta-tarsi elongated.