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jugal bones ; the mandible being united to the cranium by elas¬ 
tic laminae. The two mandibles move upon each other by 
means of an intermediate bone placed at their articulation. 
The organ of smell is situated at, or near the base of the bill, 
generally hidden by the feathers. 
The tongue has but little muscular substance, and is support¬ 
ed by a production of the hyoid bone. Most birds seem not to 
be possessed of a fine degree of taste. 
The eyes of birds are so constructed, that their sight is very 
acute, whether near or at a distance. In addition to the ordi¬ 
nary eyelids, there is a membrane which acts like a curtain to 
cover the eye. 
Birds which fly by day seldom have an external ear; but noc¬ 
turnal birds possess that organ, although not nearly so much 
developed as that of tpiadrupeds. It is generally covered by 
barbed feathers, which are more fringed than those of their 
body. 
The brain of birds agrees in character with that of the other 
vertebrate oviparous animals, but remarkable for its volume, 
being proportionally greater, and even exceeding, in many cases, 
that of the mammalia. This increased bulk is attributable to 
tubercles, which are analagous to the corpora striata, and not to 
the hemispheres themselves, which are rather compressed and 
without circumvolutions. The cerebellum is largely developed, 
nearly without lateral lobes, and consisting almost entirely of 
the vermiform process. 
The trachea is formed of entire rings. At its bifurcation is a 
glottis, furnished with a set of muscles called the lower larynx. 
This organ produces the voice of birds, which has great compass 
owing to the large volume of air contained in the air vessels. 
The voice is modified by the length and width of the trachea. 
The upper larynx is very simple. 
The anterior extremities, or wings of birds, are formed for 
sustaining them in flight, but are neither adapted for prehension 
nor standing. The body has a forward inclination, and the 
toes are considerably produced, to assist in sustaining them in 
an upright posture. The pelvis is much elongated, in order to 
furnish attachment to the muscles which support the trunk 
upon the thighs. There is also a beautiful provision in nature, 
by which birds are enabled to sleep with certainty perched on 
