ANSERINE. CYGNUS. 155 



base and margins, as well as part of the upper surface, 

 fringed with tapering horny papillae, the tip thin, horny, 

 rounded ; oesophagus extremely long, narrow, dilated a little 

 toward the fureula ; proventriculus bulbiform ; stomach an 

 extremely developed, oblique, transversely elliptical gizzard, 

 of which the lateral muscles are extremely thick, their 

 tendons large, the epithelium forming two very thick, con- 

 siderably concave, grinding surfaces ; intestine long, rather 

 narrow, arranged in sixteen folds ; coeca long, narrow at 

 the base, then of moderate width ; cloaca oblong. Trachea 

 considerably flattened, a little enlarged below, with the 

 syrinx much compressed ; the bronchi wide, enlarged, 

 near the end. Nostrils elliptical, medial, near the ridge. 

 Eyes small. Aperture of ear small. Legs short, stout, 

 placed a little behind the centre of equilibrium ; tibia bare 

 for a very short space ; tarsus considerably compressed, 

 reticulated ; hind toe very small and elevated, compressed 

 beneath ; anterior toes longer than the tarsus, the outer 

 two nearly equal ; all scutellate, unless toward the base ; 

 membranes full ; claws strong, arched, compressed, rather 

 obtuse, that of the third toe expanded and rounded. Plu- 

 mage moderately full, close, firm, unless on the head and 

 neck ; wings very long, rather broad, convex, of about 

 thirty-two quills ; the second and third longest ; tail short, 

 rounded, of from eighteen to twenty- four feathers. 



The Swans inhabit chiefly the temperate /and cold parts 

 of the globe ; breed in the glacial regions, laying numerous 

 elliptical, generally greenish- grey eggs. They walk slowly, 

 but swim gracefully ; sometimes feed on shore, but usually 

 in the water, on the roots and submersed stems of plants, 

 which their very long necks enable them to reach. Their 

 food consists entirely of vegetable substances. In most of 

 the species, the trachea enters the keel of the sternum and 

 returns, before proceeding to the thorax. The young are 

 generally grey, the adult white ; but one species, the Aus- 

 tralian, is black. In the adults is a large bare space at the 

 base of the bill, extending to the eyes ; but in the young 

 it is covered with very small foathers. 



