INTRODUCTION. IX 
under surface of the bones. Their organs of motion are 'two wings 
and two legs ; and they are destitute of external ears, lips, and 
many other parts which are important to quadrupeds. That part 
of zoology which treats of Birds is called Ornithology. 
Linnaeus divided this class into six Orders. 
ORDERS OF BIRDS. 
1. L.ind Birds. 
I. RAPACIOUS BIRDS (Accipitres.) Having the upper mandible 
hooked, and an angular projection on each side near the 
point, as the eagles, hawks, and owls. 
II. PIES (Piece .) Having their bills sharp at the edge, somewhat 
compressed at the sides, and convex on the top, as the crow. 
III. PASSERINE BIRDS (Passeres.) Having the bill conical and 
pointed, and the nostrils oval, open, and naked, as the spar- 
row and linnet. 
IV. GALLINACEOUS BIRDS (Gallince.) Having the upper man- 
dible arched, and covering the lower one at the edge, and the 
nostrils arched over with a cartilaginous membrane, as the 
common poultry. 
2. Water Birds. 
V. WADERS (Grallee.) Having a roundish bill, afleshy tongue, and 
the legs naked above the knees, as the herons, plovers, and 
snipes. 
VI. SWIMMERS (Anseres.) Having their bills broad at the top, 
and covered with a soft skin, and the feet webbed ; as ducks 
and geese. 
Under the third class, or Amphibia, Linnseus arranged such ani- 
mals as have a cold, and, generally, naked body, a lurid colour, 
and nauseous smell. They respire chiefly by lungs, but they have 
the power of suspending respiration for a long time. They are ex- 
tremely tenacious of life, and can repair certain parts of their bodies 
which have been lost. They are also able to endure hunger, some- 
times even for months, without injury. 
The bodies of some of them, as the turtles and tortoises, are pro- 
tected by a hard and horny shield or covering ; those of others are 
clad with scales, as the serpents, and some of the lizards ; whilst 
others, as the frogs, toads, and most of the water-lizards, are entirely 
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