78 THE STRUCTURE AND LIFE OF BIRDS cumap. 
Breathing Apparatus and Pneumatic Bones. 
A bird’s breathing apparatus is of the first order. 
‘When a lark is rising, his wings are beating at the 
rate of quite two hundred strokes per minute, probably 
much faster. And yet all the while he sings as if he 
were making no great muscular effort. I recommend 
any one who does not appreciate the marvel of this to 
try to run up hill and sing or shout at the same time. 
Of all those who make this experiment we may quote 
what Vergil says of the Greek ghosts in Hades, who 
try to raise their war-cry when A®neas appears :—- 
Inceptus clamor frustratur hiantes. 
On the floor of the mouth just behind the tongue is 
the glottis or opening into the trachea or windpipe, 
a tube formed of rings of bone and gristle which runs 
along the neck to its base, where it divides into two 
bronchi, which lead, one to the right, the other to the 
left lung. The epiglottis, which springs from the 
anterior end of the glottis, and the function of which 
in mammals is to close the opening during the process 
of swallowing, is very little, if at all, developed in 
birds. Apparently the edges of the larynx, the name 
given to the upper end of the trachea, meet so exactly 
that no epiglottis or lid to the glottis is necessary. 
The larynx has no vocal chords as in mammals, hence 
it cannot produce voice, but only raise or lower a note 
by bringing together or separating the stiff margins of 
the glottis. The organ of voice is the lower larynx 
or syrinx, an organ found in no other class of animals, 
