680 SYSTEMATIC SYNOPSIS.— LAMELLIBOSTRES — AN SERES. 
unite and form a bridge across the palate. The angle of the mandible is produced and greatly 
recurved" (Huxley). The interorbital septum is more or less completely ossified, and the 
orbits are better defined than in many birds, by well-developed lacrymal and post-frontal pro- 
cesses. The premaxillary is large, and its three prongs are so extensively fused that only a 
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 piscivorous swimmers (fig. 63). The sternum is 
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 vertebr£e 
vary a good deal in number, owing to the variability of the cervicals, which run up to 24 in 
some swans. The pelvis is ample, arched and extensively ossified, with small foramina, shoMing 
nothing of the straight, constricted, largely fenestrated figure • prevalent among lower water- 
birds. The oil-gland is present, tufted. The carotids are two. The ambiens, femoro-caudal 
audits accessory and semitendinosus are present. The tongue is large and fleshy; its main 
bone (glosso-hi/al ; fig. 72) is highly developed; its sides show processes corresponding to 
the lamellae 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 typical disposition of large hemispherical lateral masses converging 
to central tendons. The coeca vary 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 Natatores which copulate on the water there is provision for more 
eflficient coitus than by simple contact of everted cloacae ; and in the Anatidce a long penis is 
developed. It is essentially a sacular production of a highly vascular part of the lining mem- 
brane 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 Anatidce 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 family, occurring in some of the cranes, ibises, certain Gcdlince, and also, it is 
said, in the curious snipe, Rhynclicea capensis. 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 
irregularly shaped capsule. Its use is not known ; in some sense it is a sexual character, 
since it is only fully developed in the male ; it varies greatly in size and shape in different 
species (figs. 3, 98). Finally, it should be added, that the pterylosis of the family is perfectly 
definite, a certain type of tract-formation prevailing throughout, with very slight minor modi- 
fications. 
It is not easy to overrate the economic importance of this large fomily. 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 compara- 
tive plenty in places where hunger often pinches the belly, and their warm dovmy covering 
is patched into garments almost cold -proof. 
The general traits of the anserine birds are too well known to require more than passing 
