Of _mottled_ and _pied_ sorts, there exists a great variety; black and white, bronze and white, lightly speckled, and many other mixtures. To this class belongs the _Rouen_--or Rhone, or Rohan, since each designation has been used--duck, which has been needlessly overpraised by interested dealers. This variety is highly esteemed by epicures; it is a prolific bird, and lays large eggs; its size is the criterion of its value. There is also a pied variety of the _Poland_ ducks, a hybrid between the white and the black, the Beaver. Another variety, known as the _Labrador_, the Buenos Ayres, or the black East Indian duck, is somewhat rare and highly esteemed by dealers. They are very beautiful birds. The feet, legs, and entire plumage should be black; a few white feathers will occasionally appear. The bill also is black, with a slight under-tinge of green. Not only the neck and back, but the larger feathers of the tail and wings are gilt with metallic green; the female also exhibits slight traces of the same decoration. On a sunshiny spring day, the effect of these glittering black ducks sporting in the blue water is very pleasing. A peculiarity of this variety is, that they occasionally--that is, at the commencement of the season--lay black eggs; the color of those subsequently laid gradually fades to that of the common kinds. This singular appearance is not caused by any internal strain penetrating the whole thickness of the shell, but by an oily pigment, which may be scraped off with the nail. They lay, perhaps, a little later than other ducks, but are not more difficult to rear. Their voice, likewise, is said to differ slightly from that of other varieties; but they are far superior in having a high, wild-duck flavor and, if well kept, are in deserved repute as being excellent food when killed immediately from the pond, without any fattening. Still another breed, known as the _Muscovy_ duck, is a distinct species from the common duck; and the hybrid race will not, therefore, breed again between themselves, although they are capable of doing so with either of the species from the commixture of which they spring. This duck does not derive its name from having been brought from the country indicated, but from the flavor of its flesh, and should more properly be termed the _musk_ duck, of which this name is but a corruption. It is easily distinguished by a red membrane surrounding the eyes, and covering the cheeks. Not being in esteem, on account of their peculiar odor, and the unpleasant flavor of their flesh, they are not worth breeding, unless to cross with the common varieties; in which case, the musk drake must be put to the common duck. This will produce a very large cross, while the opposite course will beget a very inferior one. THE GOOSE.