ANATIDiE, GEESE, DUCKS, ETC. 



279 



slight nasal aperture remains. Sometimes the top of the skull shows crescentic 

 depressions for lodgment of the supraorbital gland, the secretion of which lubricates 

 the nasal passages ; but this feature is never so marked as in most of the pisciv- 

 orous swimmers. The sternum is both long and broad, more or less transverse 

 posteriorly, with a simple notch or fenestra on each side ; sometimes its keel is 

 curiously hollowed out for a purpose stated beyond. The vertebras vary a good 

 deal in number, owing to the variability of the cervicals, which run up to 23 in some 

 swans. The pelvis is ample, arched and extensively ossified, with small foramina, 

 showing nothing of the straight, constricted, largely fenestrated figure prevalent 

 among lower water-birds. 



The tongue is large and fleshy ; its main bone (glosso-hyal) is highly developed ; 

 its sides show a fringe of processes corresponding to the lamellaj of the bill. The 

 gullet is not so ample as in the flesh-eating swimmers. The gizzard resembles that 

 of a fowl in its shape and great muscularity ; the muscles are deep-colored, and well 

 show the tjrpical disposition of large hemispherical lateral masses converging to 

 central tendons. The coeca varj' with the genera according to food ; they are very 

 long — 12 or 15 inches — in some of the herbivorous species. The male genital 

 armature merits special notice. "In some MUatores v/hich copulate on the water 

 there is provision for more efficient coitus than b}^ simple contact of everted cloacae ; 

 and in the Anatidte a long penis is developed. It is essentiallj^ a saccular produc- 

 tion of a highly vascular part of the lining membrane of the cloaca. * * * In 

 the passive state it is coiled up like a screw by the elasticity of associated 

 ligamentous structure. * * * A groove commencing widely at the base follows 

 the spiral turns of the sac to its termination ; the sperm ducts open upon papillae 

 at the base of this groove. This form of penis has a muscle by which it can be 

 everted, protruded and raised." (Owen.) Among the most interesting structures 

 of the Anatidte are the curious modifications of the windpipe, prevailing almost 

 throughout the family. In a number of swans, this organ enters a cavity in the 

 keel of the sternum, doubles on itself and then emerges to pass to the lungs, forming 

 either a horizontal or a vertical coil. In some geese the windpipe coils between the 

 pectoral muscles and the skin. These vagaries of the windpipe are not, however, 

 confined to the present familjr, occurring in some of the cranes, certain GaUince, 

 and also, it is said, in the curious snipe, Hhynchcea eapensis. In most of the ducks, 

 furthermore, and in the mergansers, the lower larynx is a singularly enlarged and 

 complicated affair ; several of the lower rings of the trachea being soldered together 

 and greatly magnified to produce a large irregularlj'' shaped capsule. Its use is 

 not known ; in some sense it is a sexual character, since it is only fullj' developed 

 in the male ; it varies greatly in size and shape in different species. Finallj', it 

 should be added, that the pterjdosis of the family is perfectly definite, a certain type 

 of tract-formation prevailing throughout, with very slight minor modifications. 



It is not easy to overrate the economic importance of this large family. It is 

 true that the mergansers, some of the sea ducks, and certain maritime geese, that 

 feed chiefly upon animal substances, are scarcely fit for food ; but the great majority 

 afford a bounteous supply of sapid meat, a chief dependence, indeed, with the 

 population of some inhospitable regions. Such is the case, for example, in the 

 boreal parts of this continent, whither vast bands of water-fowl resort to breed 

 during the fleeting arctic summer. Their coming marks a season of comparative 

 plenty in places where hunger often pinches the belljr, and their warm downy 

 covering is patched into garments almost cold-proof. 



The general traits of the anserine birds are too well known to require more than 



