the Indian barred-headed goose; and the cereopsis from New Holland.  The stately Swans from various parts of the world, all graceful; including the handsome black-necked swan, and the whistling swan, occupy the three cases next in succession (140-142).  The Ducks occupy no less than eight cases; and the visitor will linger over the beautiful varieties, without once allowing the unkind association of green peas to enter his head.  In the first four cases (143-146) are the sub-families of the true duck, collected from various parts of the world;—­the teal from China; the whistling duck from South America, and the European varieties of the common teal, the widgeon, and the sheldrake.  Three cases (147-149) are filled with those sub-families of the duck which prefer the sea or the great lakes, including the handsome red-crested European duck; the eider duck, which is robbed of its down for the comfort of mankind;[4] the scoter and nyroca ducks; and, in the third case, the spinous-tailed ducks of southern climes.  The arctic birds, known as the Mergansers, are grouped in the next case (150):  and, proceeding on his way, the visitor will arrive before the cases (151-152) of Divers, from the north, so called from the strength with which they dive for the fish upon which they live; but their powers in this respect are not equalled by those of a sub-family of web-footed birds, which the visitor will presently reach.  Before reaching the cases in which the interesting sub-families of the Gulls are exhibited the visitor should remark the varieties of the Grebes in case 152; the two following cases devoted to the Auks from the arctic regions; and the true Auks of Britain; the varieties of the Penguins, or marine parrots; and the Guillemots.  From these birds the visitor’s way lies in the direction of the six cases (155-160) in which the sub-families of the gulls are grouped.  The contents of the first cases will at once strike him:  here are the Petrels, and the associations of shipwreck and disaster with which they have ever been connected.  The group includes the stormy petrel, and the albatross.  They have an altogether wild and singular appearance.  The true gulls of every sea are grouped in the next three cases (157-159):  they come from the ice of the polar seas, and from our own shores, including the kittiwake gull, and the European black-backed gull.  The last case of the gull family (160) is given to the Terns, which are caught in all parts of the world; and the Skimmers, so called from the dexterity with which they skim the surface of the water, keeping the under mandible immersed, and the upper dry, in search of prey.  Next to the gulls are placed the Tropic Birds (161), the name of which indicates their native clime.  These birds prey upon fish; some, as the red-tailed tropic bird, darting upon the flying-fish; and others, as the darters, boldly plunging into the tide from overhanging boughs, in search of their favourite prey; here, too, is the common Cormorant.  Four more cases remain for