INTRODUCTION. 
IX 
made while they are drawing them forwards to repeat their 
ftrokes in the water. Many of thefe divers are provided inter- 
nally with a receptacle, feated about the windpipe, for a flock of 
air, which ferves the purpofe of refpiration, whilft they remain 
under water : and the whole of the tribe of fwimrners have their 
feathers bedded upon a foft, clofe, warm down ; and are fur- 
niflied with a natural oil, fupplied from a gland in the rump. 
This oil they prefs out with their bills from a kind of nipple, and 
with it preen and drefs their plumage, which is thereby render- 
ed impenetrable to the water, and, in a great degree, to the 
mofl extreme cold. 
Of the number of thefe birds, both waders and fwimrners, a 
great proportion may not improperly be termed frefli-w'ater 
birds, as they rear their young, and fpend the greater part of 
their time inland. In this clafs are the Ardea^ Scolopaxy and 
Trlngay with divided toes, — the Fulicay Phalaropusy and PodicepSy 
with finned feet ; together with others of the web-footed kinds, 
chiefly of the genera of the Mergus and Anas» Among thefe 
various kinds, fome fpecies are found, which only occafionally 
vifit the fea-lhores : others have not been noticed there at all ; 
while others are feen there frequently, feeding on the beach : 
fome, like little boats, keep within bays and creeks, near the 
fliore ; others, meanwhile, adventure into the ocean, and fport 
amidfl its waves. To particularize thefe, with their various 
places of abode, and the times of their migrations, would here 
be tedious and unneceflary ; they are noticed in the defeription 
of each bird. 
The northern extremities of the earth feem as if they were fet 
apart for the nations of the feathered race, as their peculiar he- 
ritage — a pofleffion which they have held coeval with creation. 
There, amidfl: lakes and endlefs fwamps, where the human foot 
never trod, and where, excepting their own cries, nothing is 
heard but the winds, they find an afylum where they can rear 
their young in fafety, unmolefled, and furrounded by a profu- 
