452 



NA TURA L HIS TOR Y. 



moss, roots, and leaves, in trees, and lay three or four light blue eggs, 

 coated with a chalky substance. 



Unlike most of their relatives, the darters shun the sea-coast, but live 

 in the dense swamps of warm countries. They are very timid, and are 

 easily alarmed. When frightened they drop noiselessly into the water, 

 and swim away to a considerable distance beneath the surface. 



Last of the swimming birds comes the series typified by our common 

 ducks, geese, and swans, the general appearance of which is familiar to all, 



and needs no descrip- 

 tion. One is never 

 in a doubt concerning 

 them. There is, how- 

 ever, one feature in 

 their structure which 

 needs mention. As is 

 well known, most of 

 these forms obtain a 

 large proportion of 

 their food from the 

 ooze and mud at the 

 bottom of the ponds 

 and streams, and to. 

 aid them in this, most 

 have a peculiar struc- 

 ture of the bill, which enables it to act as a sieve. On the inside of the 

 mouth are a number of plate-like teeth, which at the same time serve to 

 hold the ooze, and also to strain out the water when the head is raised. 

 The whole operation can easily be seen when one of these birds is feeding. 

 The geese, however, feed to a considerable extent on grass, and in these 

 forms these plates are modified for nipping off the grass. These teeth are 

 shown in our figure of the shoveller-duck, with which we open our account 

 of the different species. It is. so far as color goes, a beautiful species, and 

 is common to Europe, America, Asia, and Australia, but is less abundant 

 with us than it is in the Old World. It is well named ; for its bill, broad- 

 ened at the end, is a true shovel, and is used as such in stirring up the 

 mud at the bottom of the water, in the search for food. The sifting 

 lamella', too, are developed to a greater extent than in most forms. 



The mallard, distributed Over nearly the whole world, needs no descrip- 

 tion, as it is so well known to all. either in its wild state or in its domes- 

 ticated condition. The black duck of the hunters, the dusky duck of books, 



Fig. 381.— Mallard ducks (Anas boschas). 



