LAMELLIROSTRES. 
275 
posed of the urates^ phosphates^ and oxalates of lime^ ammo- 
nia, and potash, mixed with some fatty and earthy matter. 
Dead birds are often met with in it. In the arctio regions, 
where birds equally abound, the accumulations from their 
droppings are not met with ; Dr. Sutherland"^ accounts for 
the disappearance of the guano-beds from the dung being 
washed away by rains or melting snow, or it may be 
owing to vegetation, by which it becomes dissipated into 
the atmosphere, or converted into a thin coating of brown 
mould on the rock, in which grasses and other plants take 
root and flourish luxuriantly, affording shelter to myriads 
of flies and their enemies, the spiders, even on and beyond 
the 7 4th degree of north latitude.''^ 
The family Ana-TID^e contains the whole of the Ducks, ' 
Geese, and Swans, birds distinguished by their thick broad 
bill, which is high at the base, and is covered by a soft 
sensitive skin, the tip alone being covered with a horny 
nail-like appendage. The edges of the beak are cut into a 
number of thin laminae, or small teeth; and from these 
plates the family is often called Lamellirostres, The tongue 
is large and fleshy, with a toothed border. This beak, by 
the laminated structure of the edge, is admirably suited for 
^ Journal of Voyage to Baffin's Bay, etc. vol. i. p. 168. 
