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and the 'pharynx. This provision allows for equalization of air pres- 

 sure on the two sides of the tjTupanic membrane. 



The sense of smell and the olfactory apparatus are poorly developed 

 in the chicken. The sense of iaste is centered in the taste buds 

 located on the surface of the tongue and on the dorsal palate. This 

 sense is only fairly developed. Touch is distributed over the skin 

 and in certain feathers. The edge and point of the beak are sen- 

 sitive to touch. Herbst's touch corpuscles are found in all parts 

 of the skin. 



Skeletal System 



The skeleton of the bird is remarkable for its rigidity with light 

 weight. Even in the heavy, nonflying chicken, this is noticeable. 

 The strongly keeled sternum serves as the attachment for the strong 

 pectoral muscles which are so important in the flight of most birds. 

 There are short bracing bones between the ribs, called uncinate 

 processes. Many of the bones, even in a chicken, have air cavities 

 in them. These are better developed in the better fliers. Teeth are 

 entirely lacking in the adult. 



The skull is quite well developed and has a relatively large cranial 

 cavity. The orbit is also large. The cranium consists of three single 

 bones, the occipital, the ethmoid, and the sphenoid. There are also 

 three pairs including the frontals, the parietal, and the temporal. 

 The free quadrate connects the lower jaw with the cranium. 



The long flexible neck is composed of sixteen cervical vertebrae, 

 the anterior two of which are named the atlas and the epistrophei's 

 (axis). The articulation of the vertebrae is such that the head is 

 well adapted for use in feeding, fighting, and nest building in some 

 birds. The centra of the vertebrae are heterocoelous or saddle-shaped. 

 Following the cervical vertebrae there are five thoracic, thirteen 

 lumbosacral, and seven coccygeal in order. The total number is 

 forty-one. The cervical and coccygeal alone have free movement. 

 The pygostyle at the caudal end supports large tail feathers, which 

 are movable. There are seven pairs of ribs, two of them articulating 

 with cervical vertebrae and five pairs related to thoracic vertebrae. 

 The thoracic ribs join the sternum by sternal ribs. The cervical ribs 

 are floating. The sternum joins the pectoral girdle by a union in 

 front with the coracoid. The coracoid articulates dorsally with the 

 scapula, another girdle bone, and with the humerus of the wing. 

 Besides the scapula or shoulder blade the two clavicles join the upper 



