conducted either in one long string or in a wedge-like phalanx. The power of locomotion displayed by these birds is very various; some species can walk upon dry ground almost as well as the Geese, while others waddle along with considerable difficulty. All are excellent swimmers, but they only dive exceptionally, and with considerable effort. Their flight is accomplished by rapid movements of their wings, and they are able to rise as easily from the surface of the water as from the ground. Ducks subsist upon both animal and vegetable food; some, however, prefer the former, while others confine themselves to the latter diet. They are for the most part monogamous, and generally associate during the breeding season in great numbers; a circumstance in which they differ remarkably from the Swans and Geese. Some build their nests in holes in the ground or in the clefts of rocks; others in hollow trees, or even among the branches, some making use of the deserted nests of land birds; while others build upon the ground a rude structure composed of stalks and leaves, warmly lined with down. The number of eggs varies in different species from six to sixteen; the period of incubation extends from twenty-one to twenty-four days. [Illustration: _Plate 36. Cassell's Book of Birds_ CASARCA RUTILA ____ RUDDY SHIELDRAKE (_about 1/3 Nat. size_)] [Illustration: THE SHELDRAKE (_Vulpanser ladorna_). ONE-FOURTH NATURAL SIZE.] THE RUDDY SHELDRAKE, OR BRAHMINY DUCK. The RUDDY SHELDRAKE, or BRAHMINY DUCK (_Casarca rutila_), represents a group possessing slender bodies, moderate-sized wings, and somewhat remarkably coloured plumage, which differs but little in the sexes. In this species the body is almost entirely of a bright rust-red; the cheek is yellowish white; the neck reddish yellow; the wing is decorated with a glossy green patch, and has its covers of a pure white; the margins of the wings, upper tail-covers, quills, and tail, are glossy greenish black. During the breeding season the male has a clearly-defined band of greenish black on the lower throat; the female rarely exhibits this collar, and is smaller than her mate; her entire plumage is also less brightly coloured, and her face of a whitish shade; the eye is light brown; the beak black; and the foot lead-grey. This species is from twenty-four inches to twenty-five inches long and forty-four inches broad; the wing measures sixteen inches, and the tail seven inches. The Ruddy Sheldrakes inhabit Central Asia, and from thence spread in an easterly direction to the Upper Amoor, and westwards as far as Morocco. In the course of their wanderings they are pretty regular visitants to Greece and South Italy. As winter guests they are well known throughout the Indian Peninsula, and are by no means uncommon upon the lakes of Egypt. In Tunis, Algiers, and Morocco they are abundant, but do not apparently extend their range into the interior of Africa. The gait of this beautiful bird is light and elegant;