2 
VERTEBEATA. 
winter, which compelled them to forsake us for more favored climes! Their songs, now heard 
from the leafy groves and shadowy forests, inspire delight or recollections of the pleasing past in 
every breast. How volatile, how playfully capricious, how musical and happy, are these roving 
sylphs of nature, to whom the earth, the air, and the waters, are almost alike habitable. Their 
lives are spent in boundless action, 
and nature, with an omniscient benev- 
olence, has assisted and formed them 
for this wonderful display of perpetual 
life and vigor in an element almost 
their own."* 
A careful examination of the struc- 
ture of birds will show us that while 
the vertebrate form is preserved in the 
skeleton, there is a wonderful adapta- 
tion of all the parts to the life these 
animals are to lead. The prodigious 
strength necessary to the wings is se- 
cured by powerful muscles attached to 
the sternum or breast-bone. As they 
are to sustain themselves in the air, 
the requisite lightness is obtained by 
making the bones hollow and the cov- 
ering of feathers. In order to facili- 
tate respiration, which would otherwise 
be obstructed in the rapidity of their 
flight, the air is not confined to the 
lungs, as in other animals, but passes 
through into various membraneous 
cells exterior to the heart, and in some 
cases is extended even down the wings. 
Birds, as well as quadrupeds, may 
be generally divided into two great 
classes, according to their food, some 
SKELETON OF sPARBow-HAwK. bclug CamivoTous^ as eagles, owls, and 
O; ThStted^Kndicate the extent of the anchySrvS-tTbrfonhe back. VulturcS, and oth ers being GranivOTOUS, 
D, The caudal vertebrse ; the letter is placed on the plowshare or rump-bone. 
E, Eibs. F, Sternum, or breast-bone. G, Furcula, or merry-thought. 
H H Clavicular, or coracoid-bone, \ -p^^.^^ sidesman. 
H*, Scapula, or shoulder-blade, j =■ 
I, Humerus, or bone of the arm. 
K, Ulna, ( Bones of the fore-arm: on the ulna is the place of insertion of the 
L, Radius, f secondary quills. 
M, Metacarpal bones, part of the hand which carries the primary quills. 
N, Phalanges of the fingers. 
0, Ilium, I 
P, Pubis, V Bones of the pelvis. 
Q, Ischium, ) 
K, Femur, or thigh-bone. o o, Patella, or knee-pan. 
S, Tibia and fibuia, or les-bones consolidated. T T, Os calcis, or heel-bone. 
T V, Metatarsal, or shank-bones. W W, Toes. 
as quails, grouse, pheasants, and do- 
mestic fowls; many, also, hold a mid- 
dle place, and may be called Omniv- 
orous. Taken together, the food of 
birds is extremely yaried, including 
fish and flesh, amphibia, reptiles, in- 
sects, fruits, grains, seeds, roots, and 
herbs. In the structure of the digest- 
ive organs, they exhibit a great uni- 
formity. The cesophagus, which is often very muscular, is usually dilated into a large sac, called 
the Crop, at its entrance into the breast ; this is abundantly supplied with glands, and acts as a 
sort of first stomach, in which the food receives a certain amount of preparation before being sub- 
mitted to the action of the proper digestive organs. A little below the crop the narrow oesopha- 
gus is again slightly dilated, forming what is called the ventriculus succenturiatus, the walls of 
which are thick, and contain a great number of glands, which secrete the gastric juice. " 
Below 
* See " Manual of the Ornithology of the United States and Canada," hy Thomas Nuttall, Cambridge, Massa- 
chusetts. 1834. 
