20 
INTRODUCTION. 
Their lungs are small, and incapable of much dilatation, but 
they communicate by apertures, with cells or membranous i 
sacs situated in the chest, and among the mtiscles, and be- 
tween them and the skin, and even with the cavities of the 
bones. Hence their respiration is said to be double. They : 
have an internal skeleton, for the support and motion of the l| 
parts ; are furnished with muscles, or organs subservient to j 
motion ; with three double organs of sense, namely, eyes, 
ears, and nasal cavities ; with a tongue, which is partly 
an organ of taste, partly of prehension, and with a general j 
sense of touch or feeling situated in the skin. Organs of ! 
assimilation, for the conversion of external substances into j 
their own nature, and of propagation, for the continuance 
of their species, are also to be enumerated ; together with 
other parts, which require to be somewhat particularly ex- i 
plained. For this purpose, let us take any bird, in which 
the external parts are easily distinguished, a Shrike, for i 
example. ; 
A bird may be divided into the head, a ; the neck, h ; 
the body, cc ; the tail, ; the anterior extremities or wings, ! 
ee ; and the posterior extremities, or legs and feet,//. The 
Head is composed of the brain, its membranes, the bones of 
the skull and face, the organs of seeing, hearing, smelling, { 
and tasting, with those for the prehension and swallowing of j 
food, and various other subordinate parts. The Neck is the i 
more or less elongated and flexile part by which the head 
is joined to the body, and is composed of the cervical ver- j 
tebrse, various muscles, the oesophagus or gullet, the wind- 
pipe, nerves, and bloodvessels. The Body is the basis of 
the whole, consisting of the dorsal and sacral vertebrae, the || 
ribs, the breast-bone, the clavicles, the heart, bronchi, lungs, ^ 
liver, stomach, intestines, kidneys, genital organs, and va- i 
rious other parts. The Tail is composed of the caudal or 
coccygeal vertebrae, their muscles, and the tail-quills. The 
Anterior Extremity consists of the bones of the scapula or' 
