346 NATATORES. FULIGULA. 
the laminated plates are larger and coarser, and entirely 
concealed by the margins of the mandibles. In general form 
they are also much shorter, thicker, and more depressed ; 
and the backward situation of the legs, with the great size 
of their feet, make them move awkwardly and badly on 
and. They swim well, though apparently deep in the wa- 
ter, from their flattened shape; and they are excellent divers. 
It is in this latter mode, indeed, they obtain the chief part 
of their food, consisting of aquatic plants and their roots, aS 
well as mollusca and worms. They inhabit the rivers and 
lakes of the interior of the country, and some of them are 
occasionally found on the sea-coasts. The tracheal organi- 
zation of the whole genus is upon one uniform plan, and the 
differences are only such as might naturally be expected in 
distinct species. 'The lower extremity or labyrinth consists 
of a bony box, or, as it is called, Orca, formed by the en- 
largement and ossification of the lower larynx; from the 
bottom of which the right bronchial tube issues. On the 
left side of the orca, and attached to it, is a large orbicular 
compressed chamber, called the Tympanum or Drum, formed 
by a bony arch, more or less covered by a thin membrane ; 
and to the base of this the left bronchial tube is attached. 
The flight of the members of this genus is rapid, and sus- 
tained by quick strokes of the wings; and is often at a great 
elevation in the air. Their colours are generally plain, and 
not possessing much variety; and none of them have the 
metallic lustre on the secondary quills that distinguishes 
most of the Anatine, which in them has been appropriately 
termed the Beauty Spot, or Speculum. 'They are natives of 
the Arctic Regions, passing the summer in very high lati- 
tudes; and in the winter their equatorial migrations are 
more or less extended according to the severity of the season. 
Their flesh is tender and palatable; in some species of fine 
flavour, as in Fuligula Vallisneria, from North America. 
