CRIBRATORES. SIFTERS. 573 



times having enlargements of various forms ; the lower larynx 

 small or moderate, compressed, or bulging out into curiously 

 varied bony sacs or cells. 



Differences in habits are also conspicuous. Thus some, 

 as the Geese and Swans, feed entirely on vegetable sub- 

 stances ; others, as the Pochards, chiefly on shell-fish. Some 

 resort to fresh-water marshes, lakes, or rivers, while others 

 are peculiarly marine. Most of them nestle on the ground, 

 but some on rocks, and even on trees, or rather in their 

 decayed cavities. Some make a plain nest of rushes, grass, 

 and other plants ; but others line the nest with down which 

 the female plucks from her breast. Some are easily domesti- 

 cated, while others seem untameable. Their flesh, too, varies 

 in quality, depending on the nature of the food. 



As the species graduate into each other, both in form and 

 in habits, from the grass-eating Geese to the fish-eating 

 Harelds, it is difficult, notwith standing the facility of de- 

 scribing species afforded by the diversities above alluded to, 

 to divide this large group into sections. In fact, neither 

 families nor genera can be strictly defined among them ; so 

 that, were it not to facilitate the examination of a group, 

 numerous and rather difficult sometimes to be individually 

 distinguished, it might be expedient to leave it undivided. 

 At first sight a Goose seems sufficiently different from a 

 Duck, to induce one to suppose that Geese and Ducks form 

 distinct families ; but, then, birds present themselves which 

 one may call a Goose, another a Duck, and a third neither. 

 However, I think we may venture on assuming four fami- 

 lies — Geese, Swans, Ducks, and Pochards. 



The Geese, Anserine, have the body ovate, large, and 

 full ; the neck long ; the head small ; the bill stout and 

 somewhat conical ; the legs rather long ; the wings of great 

 length and breadth. They feed entirely on vegetable sub- 

 stances. 



So do the Swans, Cygnin^:, which, however, have the 

 body very large and elongated ; the neck excessively long, 

 but the feet very short and thick ; the bill rather long, and 

 of equal breadth throughout. 



The Ducks, properly so called, or Anatin^e, have a rather 



