This species, in a wild state, always pairs, but in domestication it becomes polyga mous, and the care of the young is left entirely to the female. It has been long common in the poultry-yard, being valued for its eggs and its flesh; and there are breeds, as the Aylesbury D., etc., remarkable for their great size and delicacy of flesh. In situations where they have ready access to a lake, pond, or stream, ducks are easily managed, and very useful poultry. In other circumstances, they cannot be kept with advantage.
The species most nearly allied to the common D. is said to be the JAVANESE DEC& (A. Javanensis). The BLACK DUCK or DUSKY DUCK (A. obscura) of North America is also very nearly allied to it, and is generally distributed from Labrador to Texas. The summer D. or wood D. of North America, and the Mandarin D. or Chinese D., belong to a nearly allied genus or sub-genus (dendronessa), with shorter bill and pendent occipital crest. See SUMMER DUCK. The TREE DUCK, or WHISTLING DUCK, of the warmer parts of America, also belongs to a distinct but nearly allied genus or sub genus (dendrocygna).
Ornithorhynchus, or Platypus, a genus of mamraalia, of the order mono tremata (q.v.). Only one species is fully ascertained, 0. paradoxes or P. anatines. It inhabits the rivers of Australia, Papua, and Tasmania. In the Australian colonies it is generally called WATER MOLE. The first descriptions of this singular quadruped were received with incredulity, and even when a stuffed specimen was brought to England, it was suspected to have been ingeniously fabricated. The whole length, including bill and tail, is usually from 20 to 23 inches. The body is rather long and compressed, thickly covered with very glossy hair, among the roots of which there is a layer of soft short waterproof felt or wadding. The head is small and round, with small bright eyes, and no external ears, although the internal ears are perfectly developed, and the hear ing acute; and instead of the muzzle, mouth, and teeth of an ordinary quadruped, the creature is furnished with a bill like that of a duck, but broader in proportion, near the extremity of the upper mandible of which the orifices of the nostrils are placed. The bill is covered with a leathery membrane. There are no true teeth, but the bill has small transverse laminae, like the bill of a duck; and at its base, on each side of each jaw, are two horny protuberances without roots or bulbs. The tongue is beset with villosities, does not extend to the extremity of the bill, and bears at its base what has been described as another tongue of a thicker form, and with two little fleshy points in front. The legs are short; the fore-feet have each five toes, with
strong burrowing claws, and a connecting membrane for swimming, which extends even beyond the claws, but is capable of being folded back, so as not to impede their use in burrowing. The hind-feet are smaller than the fore-feet; they have each five toes armed with claws, and webbed, but the web does not extend beyond the base of the claws. The hind-feet of the male are armed wills sharp spurs, like those of a cock, which are merely rudimentary in the female. These spurs were at one time erroneously supposed to be venomous. The tail is strong, broad, and flattened, about half as long as the body, covered with longer and coarser hairs, and nearly naked on its under sur face. The duck-bill, besides the characteristics of the monotremata, exhibits other ana tomical peculiarities which resemble those of birds, and some—principally osteological —which even resemble those of saurian reptiles. It lives chiefly in the water, and seeks its food by means of its bill in the mud, like ducks. Its food consists chiefly of aquatic insects, mollusks, etc.; but it is said also to feed on small fish, and even on vegetable food; and in confinement, it can be fed on worms, mince-meat, or egg, and bread and milk. It makes serpentine burrows of great length-20 or even 50 ft. —in river-banks, entering near the water's edge, and enlarged at the termination into a receptacle or nest, which is furnished with dry weeds for the accommodation both of parents and young. The young are produced in a very imperfect state: the duck-bill is indeed strictly ovoviviparous; the fetus receives no nutriment from the parent before birth, except what it derives from the ovum, which, however, is hatched within the body of the parent; but the young are suckled, and the mouth is adapted to this by the comparative shortness of the bill and greater length of tongue at this period of life. The duck-bill is lively and active, and ,so readily alarmed by the appearance of danger as not to be easily shot, diving before aim can be taken. It is. usually to be seen with only its head above the surface of the water. It prefers the twilight to the glare of day. Its voice resembles the growl of a small puppy. It carefully dresses and Becks its fur. When asleep, it rolls itself up into a ball.