THE RESPIRATORY SYSTEM, 215 
muscles. They speak with the aid of their tongue and beak 
alone. The syrinx may be altogether absent, as in the American 
Vultures and in the Ostrich and its allies. 
The Jungs are two oval flattened organs fixed in and imbedded 
between the ribs from the second dorsal vertebra to the kidneys. 
Their texture is loose and spongy. The two bronchi penetrate 
their anterior surface, and divide into four or six branches ter- 
minating by side openings on the surface, which openings com- 
municate with air-sacs, which are usually nine in number. 

Diacram or A Loputz or THE Lune or A Brrp: greatly magnified 
(after Thomas Williams). 
Normally one of these is situated between the clavicles, and 
gives out a process on either side which, passing into the avilla 
or “arm-pit,” enters the humerus*. ‘Two others penetrate 
the abdomen, and often enter the sacral vertebree and each 
femur; four permeate the more anterior region of the trunk, 
and two go to the neck. The latter often send branches into 
the bodies of the cervical vertebre. These air-sacs do not 
supply air to the cranial bones. These are supplied from the 
nose and the cavity of the outer part of the ear. 
* John Hunter tied the windpipe of a fowl and then divided the humerus, 
and he found that it breathed through the aperture in that bone. 
